I installed the 32-bit version of Windows 7, then Avast, then 64-bit W7, then Avast again. Then, after posting my question, I uninstalled Avast and reinstalled it. As I had noted, though, the first Avast install did have duplicate folders.

It appears that the second OS install (the first was to a new drive) did not clear the drive.

I will do a wipe and start over when I have time.

One question though. Does DBAN wipe every drive in the computer, or does it let you select which partition? I have the primary drive split into two partitions and only want to wipe the C drive.

Many thanks for your help.