Well, in defense of the 7900GT, it's pricing lately has made it an even better option than ever. It is a great buy, just not for $350.
Buy.com had one for under $220 AR which pretty much matches the best price I've seen for the 256MB X1800XT. One thing seems clear, 7900GT, X1900GT, and X1800XT 256MB are all about the same price through Newegg now, which IMO they need to stay down under $250 or the X1900XT gets in the way. WOuldn't these all be nice cards if they drop to $200. And it would seem that the newest card of the bunch, the X1900GT takes the back seat by a little.
You know, I can't comment on the X1900XT cooler noise, but my Sapphire X1800XT is pretty stinking quiet through all my gaming so far. My room temps have gone up, and last night during Oblivion was the first time I heard the card ramp up above the 49% mark (except whn I changed it in ATI Tool). I agree with you, I sure would like the X1900XT Ice Q model and at an extra $40 with Flatout, it would be very tempting if I were buying today.