Only at about 1GB of RAM you'll start getting smooth gameplay. I had 768MB at first but I had to buy extra 512MB because it was so annoying to play. But no amount of RAM can help you with AH/mailbox lag.
Just curious, as I haven't played WoW for a few months now, does AH and/or mailboxes still lag a lot at peak hours?
It was very frustrating to play when you had to wait few mins to read your mail or search AH.
