For the last three years I've been using OnTracks Fix-It Utilities and am very happy with its virus scanner and tools.
Updates have been free for all three years. The virus program finds not only virus on my machine, but also on the lan at home.
But I especially like its tools for the registry. I take good care of my computer, but they have a program called "Registry Fixer" that straightens out your registry. First time I ran it it found 1600 errors on a computer that was less than six months old.
It also has a registry defrag that speeds up the computer. Not to be confused with the basic scandisk/defrag on the hard drive.
I have learned though, that when I use OnTracks defrag (Slightly better than MSN's" program, I have to control alt delete all open programs except systray and explorer; otherwise the defrag program will hang.