Hows that AntiVir at updating now, i used it about a year or so ago, but it stopped updating, would never connect so i just got shot, and now using AVG 7.5.
I think the slow updates have been fixed. I never had any problems and it usually took less than 10 secs to update.
As for the frequency of the updates, they are every 24 hours on the Classic version (you can change update options in the configuration). I used the Premium version for a while and it updated 3-5 times a day.