I use Avast!4Home and never got a warning about GameZebo - did you try contacting AVG?
To assume the problem is with GameZebo isn't really fair - sometimes your anti-virus will read things as a trojan that doesn't exist. Norton's used to be really bad for that.
If your AVG said GameBoomers had a virus, would you just automatically believe it? Contact AVG and see what they tell you. You might just be surprised.
Or you can just stay away from GameZebo. But I have been several times since this posting and never a problem yet *knock on wood*
Just IMHO.