I used to run FSOpen MediaVPs on a Mobility Radeon (no extra letters or numbers--yes, it was that crappy)
It worked well, actually. Back then, VPs were split up into textures, models etc. I turned off models and advanced, and it ran very well. Oddly enough, newer textures were often used on retail meshes, which still looked better than standard, and all engine/weapon/hit effects were all VP level.
Not sure if that's still possible what with our new mv_assets package, but you could use VPview or something to extract out things.
Another thing though is that the 6600 would have been much much better than my old crappy card/integrated, so the extra poly count might not rape your performance.
Speaking of which, it'd be kind of neat to have a low-spec pack that ran textures at half size, and made all ships max out detail at LOD1. Of course, this means that LOD1s for almost everything would need touching up, but it would allow lots of flexibility for older or nongaming computers.