Just thought I'd share some of the info I have found about processes and mem usage over the years. Before I go any further, I just want to give the usual: "I am not responsible for any damage you do to your system by using the following information. Do not email me for help as I wont respond."

Ok off we go.....You can go straight to Other(ie non win2k base processes) by clicking HERE

First of all, almost all of the processes listed here can be stopped by editing the Window's registry key at "HKEY_LOCAL_MACHINE \ SOFTWARE \ Microsoft \ Windows \ CurrentVersion \ Run". If you are comfortable editing the registry, then please go ahead and do. For those that haven't done it before, all you need to do is go to Start--->Run and type "regedit" without quotes. Please be aware that you can SERIOUSLY disrupt windows if you delete/edit the wrong keys, and can even stop your system from loading windows at all.

Win2k Default/Base Processes (DO NOT try to kill these!) | Name in Task Manager | Purpose | Can be killed?
System Idle Process | System Idle Process | This process is a single thread running on each processor (if you have an SMP system).It's sole task is to account for processor idle time when the system isn't processing other threads. In Task Manager, this process to should account for the majority of processor time. | Nope
System | System | Most system kernel-mode threads run as the System process, i.e its damn important. | Nope
Session Manager Subsystem | SMSS.exe | Responsible for starting the user session. Initiated by the system thread and responsible for various activities, including launching the Winlogon and Win32 (Csrss.exe) processes and setting system variables. After it has launched these processes, it waits for either Winlogon or Csrss to end. If this happens "normally," the system shuts down; if it happens unexpectedly, Smss.exe causes the system to stop responding (hang). | Yes, with great difficulty, but then your system hangs. So don't kill it.
Client/Server Run Time Subsystem | CSRSS.exe | This is the user-mode portion of the Win32 subsystem (with Win32.sys being the kernel-mode portion). Essential subsystem that must be running at all times. Csrss is responsible for console windows, creating and/or deleting threads, and some parts of the 16-bit virtual MS-DOS environment. | I couldnt kill it. Best not to anyway :)
Winlogon | Winlogon.exe | This is the process responsible for managing user logon and logoff. | Never tried, best not to.
Services Control Manager | Services.exe | This is the Services Control Manager, which is responsible for starting, stopping, and interacting with system services. | Nope, ya need this.
Local Security Authentication Server | Lsass.exe | Generates the process responsible for authenticating users for the Winlogon service. Performed by using authentication packages such as the default Msgina.dll. If authentication is successful, Lsass generates the user's access token, which is used to launch the initial shell. Other processes that the user initiates inherit this token. | Need this too.
Svchost.exe | Svchost.exe | A generic process, which acts as a host for other processes running from DLLs; therefore, don't be surprised to see more than one entry for this process. To see what processes are using Svchost.exe, use Tlist.exe from the Windows 2000 CD-ROM; the syntax is tlist -s at the command prompt. | Not on your nelly.
Spooler Service | Spoolsv.exe | Responsible for managing spooled print/fax jobs. | Nope.
Winmgmt | Winmgmt.exe | Core component of client management in Windows 2000. Initializes when the first client application connects or continuously when management applications request its services | No way.
Explorer.exe | Explorer.exe | This is the user shell (the taskbar, desktop, and so on). This process isn't as vital to the running of Windows as you might expect, and can be stopped (and restarted) from Task Manager, usually with no negative side effects on the system. BUT there is no reason to do so and makes things unstable. | I wouldnt.
Other Processes (kill most of these) | Name in Task Manager | Purpose | Can be killed?
qttask.exe | qttask.exe | As IE5.5 SP2 and IE6 no longer support Netscape style plugins, Apple made a Quicktime Active X Control to ensure Quicktime movies still ran in-browser. These program basically lets the Control work with older browsers, and also re registers MIME types to Q.Time. | Yep. Basically, if you have IE 5.5 or 6, and quicktime 5, disable it in the registry place listed above, and delete the damn thing.
Microsoft Query manager | loadqm.exe | Microsoft says that this is an autoupdate utility for MSN messenger and MSN explorer, therefore it is installed with either of those. However I have heard reports of MS Office and Outlook also installing it, and that it sends "anonymous" user statistics to MS. I checked with a firewall, and it seemed to be trying to access the net about 15 times a minute. | Yes, disable in registry, then delete the damn thing.
Microsoft Task Scheduler | MSTask.exe | The prog that looks like a little calendar in your task bar. It allows you to schedule things like defragging automtically. Personally, I disable it. | Yes, but dont delete it or go to the registry. Simply go Control Panel---> Admin tools---->Services, then disable and stop the task scheduler service in there.
Cdilla Licence System | CDANTSRV.exe | Installed for high end apps like 3D Studio Max to protect against piracy. Basically, if this aint running when you try to launch 3DS max, it wont start. | Yes, but dont delete. Go to Control Panel---> Admin tools---->Services and select Manual for Cdilla srv. That way you can start it manually when you run 3ds max or other similar apps.
Devldr16 | Devldr16.exe | Background task installed with the drivers for some Creative Labs sound cards. Provides SoundBlaster 16 emulation for DOS applications and games. Without it, your DOS games will not have any sound. Disabling this program, however, often gives problems with the general behaviour of sound and of the Creative sound utilities on your PC. For the technically minded all these problems are due to the fact that DEVLDR16 emulates old ISA sound cards which do not have the ability to share resources in the way that the newer PCI cards can. | If you do not use DOS games, and you want to get rid of this task, the only way to safely disable this task is as follows: 1) Disable in Startup Manager. 2) Next, in Device Manager, in the Sound section or under "Creative Miscellaneous Devices", disable Creative SB16 Emulation.
devldr32 | devldr32.exe | Probably a newer version of the above, though I'm not sure. It seems to appear when using the newer Soundblaster cards such as SBLive etc. I haven't checked if DOS games run when you kill this, but they probably wont as I cant see any other way of SB16 emulation. After killing it I noticed that all EAX games still worked fine, and the DX Sound tests run through ok. However, after deleting it, Windows FIle Protection kicks in and replaces it, and also without it many creative apps wont work. I'd leave it running unless you are desperate to recover about 2mb. | I cant find a way to get rid of it permanently as Windows keeps replacing. If I spent some time I could find the Reg Key in Win2k FileProtection and stop it, but I dont think its a good idea to disable it.
wowexec.exe | wowexec.exe | This is as process that helps "translate" interrupts, etc for 16 bit applications. Usually should only be running when you are running 16bit apps/dos stuff. | No point, it should dissapear when you close your 16bit app.
Nvidia Driver Helper Service | nvsvc32.exe | Cant remember what this does, and it uses sod all memory, but as far as im concerned there is no need for a GFX card to have a process running - as long as its got the right driver(s) in that's all it should need. | Yeah, disable this in Control Panel---> Admin tools----> Services.
Norton Auto-Protect | navapw32.exe | Norton Anti-Virus's background scanning process. Can be inconvenient because it scans files when Run/Opened or Downloaded/Created. Personally I have it turned off and just right click files to scan them. | Yeah, disable this in Control Panel---> Admin tools----> Services.
Norton eMail Protect | POPROXY.EXE | Proxy E-mail protection from Norton Anti-Virus (prior to 2002). If you have it installed, leave it enabled to automatically check for suspect attachments in E-mails that may contain viruses. It downloads the E-mail into poproxy, which serves as a proxy server on the local machine, before scanning it. I have this turned off too. | There is an option to disable it in NAV itself
Acrobat Assitant | ACROTRAY.EXE | This is part of the FULL version of Adobe Acrobat (ie the £150 jobby, NOT the FREE Acrobate Reader).If you want to create a PDF using Acrobat Distiller this needs to be running for you to do so. However, you can execute this program manually just before doing so. Unavailable via Start -> Programs so create your own shortcut. | Yeah, its just in the startup folder on the Start menu, so just delete it from there.
Intellipoint Software | point32.exe | Software to do "clever" things like let you use those thumb buttons on your 5 button mouse, or to use a "new" Optical MS mouse. However, ALL the newer OS's (XP, win2k with SP2 etc) have built in support for all this so there is NO reason to run this anymore. Simply plug in your mouse and it should autodetect it. | Yeah, just dont install it in the first place.
Language selection | internat.exe | This sometimes appears in the system tray as "EN", or sometimes just runs as a process. Basically its supposed to allow easy switching betweens multiple languages. If you are only going to be using one language, disable it. | Yes, in the registry, BUT it isnt in local machine its in - :"HKEY_CURRENT_USER\ Software\Microsoft\Windows\ CurrentVersion\Run".
Rundll/Rundll32 | Rundll.exe/Rundll32.exe | Microsoft’s "Run a DLL as an App". A DLL is a Dynamic Link Library. The main advantage is that, using this technique, programmers can develop software which only uses enough memory for the core functions of the program, with specific features implemented in separate DLL files only loaded as and when the end-user decides to use them (ie. the Print DLL will only be loaded into memory when the end-user clicks on PRINT). Another advantage is that the software developers can also have common features which they have implemented across a range of their programs, implemented just the one time as a shared DLL which is used by all that developer’s programs. RUNDLL and RUNDLL32 are the Microsoft Windows programs that need to be used to load DLLs into memory so that they can be used by specific programs or by Windows. This should explain why a lot of "Rundll Errors" happen on Windows - Its not a single program, but the result of any one of a number of programs. | RUNDLL and RUNDLL32 do not normally appear in the Task List in Windows. However, they do sometimes, and I think it's best to leave well alone unless you know for SURE which program has created that instance and that it can be killed safely.