I have used Norton, PcCillin, AVG, and few others but finally stuck with Avast. The reason I went with Avast is it`s the only one that really scans DivX files. If you click to scan and it takes less that a second to do 700 mgs file then nothing was scan. But with Avast try the same file and watch it go. There are other files that Avast was able to check that Even Norton 2004 would not even try.