Hi
A program you could try is Velociware Perfect Process. There is a freeware version of this (Ver 1.1) which I use without any problems. Its an anti spyware program which lists all of your running processes and gives a description of each one and what its for. It also gives you a recommendation on each one as to whether it is safe to disable it.
I find it a very useful tool which I use occassionally to check that no nasties have crept in and are running in the background without my knowledge. I would use with caution if you are unsure of anything but its relatively straight forward to use and is clear about the main processes that you should not terminate for basic windows to function. Its great for explaining what each of the processes are for.
It can be found here
VELOCIWARE(c)
Check it out -there is plenty of info about it on that page to help you decide. Hope this helps.