I don't bother with any AV stuff or utilities. What I do is setup a machine with a fresh windows install then resize the partition back ~20 gigs. Defrag windows and run a tool that consumes all the free space with a progressively growing file filled with zeroes (after which the file is deleted). I go back and install Debian in the 20 gig partition. IN there I run the two Windows partitions through gzip. Then I go and setup the boot menu and plop in a script that can uncompress and write those partitions back. Net result is that any time I want a fresh machine I just reset the box, select 'restore' from the Grub menu and wait two hours.