Someone said that 1G was a lot better for 5 instances, but I would like everyone to keep in mind that for a 32 bit operating system you reduce available system ram by 1/2G if you have a 1G card vs. a 1/2G card.

It depends on how many textures are required for a zone I guess, if over 100M per account then 1G might be better. Maybe there is a limt to the amount of textures WoW keeps on the video card as compare to system ram. Just not enough infos to know.

I use 1/2G 9600 cards and don't plan to upgrade.