Get your running processes under 20 and you shouldn't worry about lost cycles or consumed memory. I've had mine as lean as 15 running processes and been stable, but the difference between 15 services/processes and 20 is negligible (as long as they aint 3rd party TSRs or other crap) at best. I've also seen a system run AH2 just fine with 50 processes running too, so YMMV.
Edit:
MSCONFIG is a free tool built-in for Windows, and it is worth every penny, a great free tool for troubleshooting a machine that is not booting correctly. But for tweaking a box I greatly prefer this tool:
http://www.sysinternals.com/utilities/autoruns.htmlAs long as you stick to the default screen you can't get yourself into TOO much trouble. SOme of the advanced features can definitely ruin an install and require reload though...so be careful.