I have 16 gigs of ram, never fill it up.

Right now i have 6 17 inch monitors plugged into an eyefinity 6 edition radeon hd 5870. It runs them all pretty good. (I run each instance at 1280x1024. Im sure I would need more if i wanted to push out crazy res's on them. main thing i wanted eyefinity for was productivity.

Im waiting to see about the new 8 core procs. I don't think sharing ram would be an issue, since I have a pretty fast SSD, I really don't think my hard drive is the bottleneck.