I find it isn't how many processes are running that makes the difference, but which process is causing my system to run at a snail's pace. It is usually the virus checker or antispyware that gives me most problems, so I have to pause the active scanning sometimes. However, the build I am running now has only 256k RAM with Windows XP SP2 Home. It is surprising how stable the system is with virtually no crashes. Often it is my higher end systems that give me problems.