...and don't forget the tesselator and sound over HDMI, if you're all about tech specs!!
+1 on the 4850 (the 512 one, don't waste money on the 1gig one)
Well about the 1 gig 4850 is I heard that because of the GDDR3, the 4850 can't take advantage of the full gig, and shows very minimal increase over the 512 meg 4850. Though I would think its because both the Ram speed and bus width. I need to read about it again to see for sure:P