Just to update those if interested i got my card today. It works great in crossfire. The only stock difference on the cards really besides a different heat sink/fan is it is clocked like 100 or 150mhz higher or so on the GPU the mem is the same. Although i was assuming it was supposed to only come in gddr3 and not gddr2. As for performance i get about 5-10fps noticeable difference on Oblivion maxed settings and 1080i resolution. So that puts me at about 25fps avg on that which is well above my 12avg before. FarCry is just amazing now. It flys in this crossfire setup. I will take more accurate benches later if you are interested.
EDIT: BTW they are diff series chips too. My XT i am assuming is the RV530 and the 1650pro is RV535 as according to ati tool