Trash Norton and Mcaffee, uninstall that other [censored]. Keep Spybot (USE THE TEATIMER ALSO), and adaware. Zonelarm has a pro version you can grab off of usenet in a minute. The pro version has anti virus.

These are what you want to keep your system from slowing down to much.

But to cover your tracks (all least to normal onlookers) , goto webroot.com and download windows washer pro. (you can grab the full version of this off of usenet or irc also, and possible p2p)