I recently had a fun time with AVG 8
After your done "Uninstalling" it, it will leave plenty of Backup files on the PC
Don't believe me? go to Start > Search / In search, Use all files and folders and search "avg" after you start it stop it, then find your way to "Control Panel"
Open - Add or Remove Programs - Find AVG 8 And select uninstall.
Go through with it and in search watch the files go up up up that's only about 30% of whats left behind, So now if your installing something like KAV, Avast, Avira, NOD32 your gonna have to have this gone so they can work at there full potential.
To do this click on this Link -->
AVG Antivirus and Security Software - Tools downloadThere will be a (32 bit) and (64 bit) removal tool choice, Select the one that's right for you.
Double click on the file, it will prompt you to select OK by asking you if you really want to remove AVG 8. Hit OK and watch the magic
After it finishes Reboot and install your AV
I had this problem occur while I tried installing my Kaspersky internet security 2008 I was worried I wasted money
If this helps anyone at all, im glad It did so they didn't have to go through what I did removing this SOB