As for performing better... uhhh, not a single review has shown the 7800 outperforming the x1800 except in Doom 3 =/ They are very close in performance with the x1800 having a few extra FPS on every game except Doom 3.
Ok, to correct this little bit of misunderstanding. There is more than one x1800 model. This one is a 256 megabyte XL model, which underperforms the 7800*GT*. GT cards are now in the low $300 range after rebate, and in fact can be had from Dell for $285-ish if you score the 25% off SBE coupon on e-bay.
The one you're thinking about, the 512 megabyte XT model, which will not be available any time soon. Pricing on that model is open for speculation. That one arguably outperforms the reference clocked GTX models. The factory overclock models from reputable makers such as Asus, BFG et al are a less clear loss.
That being said, I'm glad NE is carrying an X1* product.