Well he said it works for 9x00 line didn't he? So whats that tell you. Put the 6 where the X would be and there's your answer.
Beedub, that's pretty cool that you're finally getting your moneys worth. I think it's what I stated from the beginning, ATI rushed out a card to compete with the 6800 and they left to many bugs in it. It's becoming appearant with better drivers the performance is increased. Have you taken advantage of some of the secrets in doom such as the ability to play the old '95 doom2
in the console to get that. Ctrl+alt+~ brings down console if you didn't know.
Also typing in iddqd will give you a secret message from the developers. If anyone remembers you had to type in iddqd before all the codes back in the day
EDIT: BTW considering my system isn't the greatest, I would say it's doing pretty well. I am running doom on high settings at 800x600 with all special effects, no AA though =/ and retaining FPS in the 40's when walking around and it'll drop down to 20's if a lot of monsters are coming out, but the lowest I've seen it drop is like 15 FPS which is pretty good considering how intensive the game is and how 'unorganized' my system is with it's mix and match RAM lol. But I got a new mobo and CPU on the way so that might squeeze out another couple FPS