With CrossFire, by design both cards always run at their individual stock or overclocked speeds, so a CF + stock X1900XTX will run faster than a CF + stock X1900XT will.
Of course, best available is an overclocked HiS IceQ3 CF card + an overclocked HiS IceQ3 X1900XT
I'm sorry, I wasn't being very clear. What I meant to say was that
the money spent on the extra speed of the xtx was being wasted. I didn't mean to say the actual
speed was being wasted. My mistake. Since a stock xtx is usually only good for a gain of 2 or 3 FPS over the xt in most games, the gain of having one in Crossfire would be even less than the xtx's gain over the xt as a single card solution.
Okay, it's 2:00 A.M. here right now and I can't quite think of the right way to phrase that, so I'm gonna quote
this article cause it says it better than I can right now.
"There was some question over whether the X1900 CrossFire would be a let down with it's XT clock speeds, but the difference between reality and the theoretical performance of 2 X1900 XTX parts in CrossFire is even smaller than the difference between the performance of an X1900 XTX and an X1900 XT."
P.S. Happy belated birthday.