Actually I take it back. DONT try to flash it, it's a 256-bit card, it wont flash to a 2900XT, but it might OC to there. I'd say they're about the same. Get the 3850 if you have a lesser PSU. EDIT: If what sammyboy says is correct then your power bill will raise hundreds if you use the 2900 pro. So in the long run it would be much better to splurge a bit more and get the 3850 512.
Like I said DONT flash it. Flashing means replacing the BIOS on the card with another one. Sam told me that the 2900PRO will consume about twice the power. You have to think about your electricity bill too. I would just get the 3850 512MB as it will consume less energy, and make less heat. It also has DirectX 10.1 support, but that's useless for now.
