Free
Won't work on my rig.
I was extremely happy with the v7 AVG free edition, so I was keen to load v8 when I upgraded to a Vista laptop. The initial download seemed clumsy, but appeared to be working. A month or so later AVG blocked the opening of Word & Excel files that I had created prior to the upgrade.
I un-installed, then re-loaded, with no success. I tried opening newer files created whilst running AVG & these were blocked. Another un-install & re-load got new files saved & re-opened just once, then blocked.
I then gave up & downloaded Avast. It works, but loses its registration number on re-booting the laptop. No I have not paid for registration. The number stays put if I just hibernate or sleep the machine, or I keep it handy to re-key via copy-paste as required.