Putting together a new system this month, and I'm down to two competing cards in my narrow price range ($250-ish). I can get a 512mb X1950PRO or a 256mb X1950XT. I'm tempted to get the 512mb card right out of the gate, but I know the 1950XT uses the new RV570 core, which is supposed to be pretty badass. Does that outweigh the memory limit though?