so would i. funnily enough though, i have a friend with a 9600XT 256Mb ram that claims to be able to run doom 3 better than i can (i have radeon 9800 Pro)
However, after running a couple of tweaks in the doomconfig.cfg file (ie, setting cache mem to 256 and all that) i can run it a lot better than he can.
go the 9800 Pro. Better overall card