I'm not sure which exact 9200 chip (as in ram and clock speeds) Ultimarc is using, but the 7000 and 9200 are not the same chip as far as I know. The 9200 has a higher clock and memory speed, more ram, 2 extra pipelines, as well as some Ati perks like smoothvision and smoothshader. Overall, the 9200 is a better chip than the 7000.
I'd have to disagree with Vicious: the 9200 could very well be a good card for 3d games. Vicious mentions the latest and greatest, but for everything else, a 9200 should perform admirably. You won't play FarCry, Doom3 or HL2 on it, but you should be able to play pretty much any 3d game around at a fair clip. If this is for a MAME machine, I doubt you'll be playing FPS's anyway. I have a mobility 9200 on my laptop, and while they are not the same chipset as the desktop 9200, as a general note, I can play almost anything on it.
As for whether it'd be worth it for you to upgrade, I guess that depends on what you value really.... this upgrade won't be a monumental change. It's very possible though that you will be able to play a lot more 3d games than you previously were, excluding today's top of the line games.
Also note, I'm talking about desktop chipsets here, not the ArcadeVGA. The chipsets are the same, but I just want to be clear that I haven't played with the 2 AVGA versions myself, but I HAVE used the chipsets before.