I am not very up to date on video cards but I am considering updating so I can play doom3. I was wondering if there is a significant difference in the ATI (Sapphire) Radeon X800 XT 256 MB ($549) or the ATI Sapphire Radeon X800 PRO 256MB ($394)? I see the price difference is almost $160. Or maybe there are some suggestions on a different less expensive card? Oh, and one dumb question - how do I tell what kind of AGP slot I have in this motherboard? thanks in advance for your help.