x2 7900GT SLi - 500$
1 X1900XT - 360$
1 7900GTX - 479$+/-
1 7950GX2 - 550~600$!!!
Get an x1900xt, its reasonably not overpriced, kicks-*** a gtx on most of applications and games, after playing on both, the AA/AF of the x1900xt on HDR looks MUCH MUCH better than on a 7900gt/x .
Oh and if you want, you could do a small overclock [25mhz on core, 50 on ram] and its as strong as an XTX.
-Jo.