GET THE RADEON X1900XTX! YOU'D BE INSANE NOT TOO!
edit: Hmm...you save $200 with 2 x 7600GTs...are they new?
With the ATI Radeon X1900XTX you save ~$300
The X1900XTX performs better too...
it also depends on the Intel processor you're getting for free, although I would still get the X1900XTX...