Video card upgrade - need advice

[falsfire3401]

So here's my situation. I recently received my new primary LCD, a 22" screen that does 1920x1080 resolution (was previously running two 17" LCDs at 1280x1024 each).

My main client runs windowed, maximized at 1920x1080 on the primary display, the two slave wow's run at 800x600 each on the 2nd screen (17" LCD).

I'm running kinda low fps now with the higher res on the primary display so I think it's time to upgrade my graphics.

I've done a bit of shopping around to find prices and such, and found two similar-priced solutions that are very different. I want to know what you guys think would work best, since I have zero experience with multi-GPU solutions.

Currently I'm running:
* a cheap board with just one PCI-Ex slot, and only 2 DIMM slots maxed out at 4gb RAM (running win7-64 so I could use more RAM if possible)
* nVidia 9600GSO 796mb PCI-Ex card
* 4gb single-channel (yuck, that's all the board does) DDR2-800


The two possible upgrades are:
* a bundle which contains a new SLI-ready nVidia chipset board, with two PCI-Ex slots, *FOUR* DIMM slots and support for more ram, and comes bundled with the exact same manufacturer/make/model of 9600GSO graphics card that I currently have
* or just buy a nVidia GTX260 PCI-Ex card for slightly cheaper


So...in terms of expandability, getting the new board would be better, I could add more RAM in the future and run my RAM at dual-channel too.

But in terms of graphics power, would two 9600GSO's perform as well as, worse, or better than a single GTX260?