Another way to find out which processes Windows needs and doesn't need is keep closing all of the processeso one by one until Windows Crashes. Then right that process down. LOL longa and hard way but it would probably work.

Also as far as stopping the processes from starting up go to start-->run-->type msconfig.
From there you should see tabs like startup, win.ini, system.ini config.sys, autoexec.bat. From these tabs you can find the programs that you don't want to start up when windows starts. However, be careful when messing with the config.sys, win.ini, autexec.bat, and system.ini. As unchecking the wrong thing in there can cause your day to go to hell.