You need moreeeeeeee ram. This weekend i started to 5 box on one computer with 2 screens (1600x1200 each)

I have my main running on 1600x1200
and my alt windows on 800x600 window 4 times.

I use 600 mb ram per window, with 4 gb ram its working but, im buying 4gb more tomorow so i dont have lag in dalaran. (thumbs up)

My config is:
8800 GTS Gforce
4gb ram atm
475gb harddisk
no clue about my motherboard, its a good one with steam pipes

Basically a gaming rig. I used to do 5 boxing on a laptop and on my pc. But it fails to switch mouses with clicking etc, so i like it better now.

But basically when you add more ram it will do fine i think.

Greets