Lose all of the SPYWARE software.
Just get Mozilla Firefox. 100% Spyware Proof.
It does not allow sites to automatically install "software" or spyware and it blocks all of the popups
If this was a perfect world, and Firefox was a perfect product, and that was the only way spyware got onto a computer, you might be right. But you're not.
Anyway, I run Norton Corp AV and the SP2 firewall as my virus defenses. After that I have Ad-Aware and SpywareBlaster for the spyware/malware/host-file stuff.