I'm just a bit scared to say this, but I've never had (to my knowledge) any of the problems mentioned on this thread. Why do some people get viruses and pop-ups and spyware and others don't?
I don't think I've got any kind of different setup than anyone else.
Go to pest patrol and run their free scan. I bet you have more than 100 pests lurking that you don't know about...yet. I fix peoples computers, and this is always my first step. Spyware is stealthware unti you run the programs you may not be aware of it.