I just had a coworker ask for recommendations on AV software. I have no experience with the 64bit so I am not sure what does and does not work on it. I searched the Avast home page and could not find if Avast works on the Vista 64 bit OS (it's probably right there I just can't find it). I did see a few threads about the boot time scan not working on this OS, which I'm not too worried about if everything else works. Again, thanks for any responses.