If you are so inclined to BUY virus/firewall/spam/spyware software; I can heartily recommend the Trend Micro Internet Security Pro suite.
When I was about to drive to McAfee HQ to choke somebody; a tech support person @ Microsoft recommended Trend Micro to me as that was what Microsoft used on their Hotmail website.
I have been using it for two years and it is WAY better than McAfee or Norton and after rebates the full blown suite is was less $$$ than either AND the license is for 3 home PC's for that same price.
Both my brother & I uninstalled AdAware & AdWatch on our PC's and I had a PAID license. AdWatch which may only come with the paid verson of AdAware; runs in the background and actively seeks & destroys adware. It caused me lots of problems with my PC and after I uninstalled the issues disappeared. Besides; the Trend Micro suite does the adware/spyware thing anyway.