Its not really that tough, and if you use FSautostart, you really can't screw anything up.
First go
HERE to get FSautostart. FS is a program you can use to shut down services and programs. That really nice thing about it is it doesn't make ANY REAL CHANGES. So if you choose to turn something off that you shouldn't, just reboot your computer and everything is back to the way it was. The program comes with a good readme file to help you set it up.
Next, open the task manager (cntrl,alt,delete) grab the bottom of the window and open it as tall as you can. Take a screen shot of the services window, print it out if you can makes it a bit easier to check stuff.
Next, goto black vipers site at that link above and go through his list, comparing it with your print out you just made. Mark on your page whether to enable, disable, or leave alone each service you can match up. For those you can't match, type it into google you'll find plenty of help and info on each (you most likely won't have to check many).
Once you have you list, start FS, and stop all the ones you can, save the profile, and fire it off. If it crashes, reboot, remove one of the shut downs and try again. Like I said you can't hurt anything.
Another thing you can do, is all those icons on the task bar by your clock.... right click them, and the items you don't use all the time, go into the properties and set it to NOT start up with windows. The less things you have down there, the less memory your loosing to run extra programs your not using.
