Hard to compare really, the Radeon absolutely blows in 16bit performance where you are stuck(though it is nearly the exact same speed running in 32bit which you should definately leave it in with a Radeon). It should be a bit faster in most games, a lot faster in others even in 16bit although the big advantage is the very sizeable jump in image quality. The V3 was the worse in 3D image quality even compared to other boards from the same generation, let alone anything current.
Got a wake up call the other day when I was playing Giants with one of my buddies on a LAN, he had a V3 and I had my GF DDR, he thought his looked fine(upgrade not too long ago from an ATi mach64<shudder>), I though it looked very, very poor- washed out, dithered, missing all sort of features, slow as hell(though his CPU didn't help that out any), blurriness bordering on obscene, horrendous texture quality and forced to run in 16bit color.