Note this recent story:
AVG Fakes User Agent, Floods the InternetSo, to spare all of us running websites, please disable this feature or do not install it. (It is pointless anyway, as discussed on slashdot, a malicious website can sidestep this easily.)
If you have already installed it you can just disable it and tell AVG not to warn you about it (right click the item in the AVG control app).
Some are recommending Avast as an alternative but it forces registration, which I consider to be NOT FREE.
ClamAV is a good solution, but has no on access scanner, but is very flexible at the command line for scheduled or scripted scans, it is more efficient if you use the distribution that includes clamd. (see my post
here.)
Note there are significant differences between ClamAV and ClamWin.