Pest Patrol, in my experience, comes up with a lot of false positives.

I agree with using Firefox or Mozilla over IE, but bear in mind that you don't have to use a browser to get a malware/scumware infection. You can simply connect an unprotected PC to a broadband connection, and within X minutes, you're infected. In some reports, X is as low as three minutes.

If you're only using one or two of these apps, I'd expect you have some things that are going undetected. Use three or four of the top ones and you'll be OK.