I use an HD2400 with Calamity's ATI drivers and groovymame and though I had to up the dotclock to 8.5, everything works perfectly
If you want to run SFIV though, steer clear of this card. SFIV runs at about 10fps and I've 2gb ram and a phenom x2 550 @ 3.1ghz.
A HD2600XT is much more like it and from what I hear light years from the crappy HD2400XT. Should perform the same with groovymame too.
BTW, the SFEX games in MAME rely on the clock speed of your CPU, not your GPU.