i have already looked at the list of supported video cards for the cube, I guess I should have asked out of the ones that do fit without modification or vrm, the 7500 and the geforce 3 (apple OEM) both fit and without modifications. If I got a 7500 the one I am leaning toward I would put a small fan to help dissipate the air like here http://www.macmod.com/content/view/24/193/

the 7500 seems a lot cooler then the geforce and is a lot cheaper but the geforce performs a bit better and I would not have to cut a custom fence.