I was interested to read a previous question on this subject as I have a similar problem. In answering, mac309 said that some of the programmes running in the background are essential for Windows operation. My question is, which are the programmes that you can't delete from msconfig? I'm a computer neanderthal so please be gentle with me!
You need systray and explorer to run Windows. I would tick the registry checker on bootup (good practice but not essential) and the systemtray (systray) since explorer is exempt from msconfig. As for the rest, leave 'em unticked.