yep, take a look at Toms vga charts. The 1900gt performs just slightly better (as far as fps) then the x850xt pe. All of the benchmarks show the x850xt and x1900gt hitting the same scores in many of the benchmarks. So, out of those, definately spend the extra cash for the 256 XT.
(I was about to get the x1900gt BTW, my opinion has since been swayed. Still a good card for its price though.)