Every time I open up my task manager and look at the tasks running, it appears to me that there has got to be a bunch of junk running in there that I don't want or need and would be better off turning off (e.g. set the service to manual vs. automatic)

In particular I'm running Windows XP, but I'd be interested in services for any version.

e.g.

Service: ThinkPad PM Service

What is it: The ibmpmsvc.exe process is installed by default on IBM Notebook computers. It allows various functions of your IBM notebook to be controlled using the blue Fn keys. If you use the blue Fn keys on your Notebook, you should leave this process running. Otherwise, if it is causing problems for your system you should terminate the ibmpmsvc.exe process. (source)

Thus for me, (having never used, or intending to use these buttons) - I want to turn it off.

There's lots that just seem painfully unnecessary to me... I'm just not sure which ones I can "safely" stop/disable without issues... "Alerter", "ClipBook", "Messenger", "Telnet", "ATI Hotkey Poller", "Office Source Engine", etc.

I'd appreciate any info on services that are truly unnecessary, or only useful to certain people/types of users.