i have 2x 260s.. crankin cards... and was getting about 20/30 fps with 1 full screen on one monitor and 2x2 on the 2nd .. each display in 1280x1024 mode. each monitor on a different card.

then i moved them all to one monitor... 1 main + 4 stack on the right using 1920x1200 resolution...
i'm now getting 50fps on each... go figure

inch:

(my next move would be to try 2 monitors from the same card... but i was happy getting it to this point, and have been caught up playing a bit...)