No such list.
Some processes are installed by individual applications...without looking at each process, there's no way to tell.
FWIW: I currently have 33 processes listed as active via Task Manager, with some being update mechanisms, AV, firewall, driver, Windows processes, etc.
I'm really surprised when people worry about this...but you can do the work (look each one up and convince yourself that you know why it's running), if you like. Google is your friend.
The svchost.exe is a different animal, What is svchost.exe And Why Is It Running the How-To Geek - http://www.howtogeek.com/howto/windows-vis...-is-it-running/
For reference purposes:
How To Determine what Services are Running in WinXP - http://www.mvps.org/winhelp2002/services.htm
How to determine what services are running under a SVCHOST.EXE process - http://www.bleepingcomputer.com/tutorials/list-services-running-under-svchost.exe-process/