No one has mentioned it yet, but the Radeon cards seem to do a heck of a lot better in 32bit. Just how they mapped there card out I guess. But anywho, if I wasn't so cheap, I would buy the Radeon...
About the question on the comparing of the V5 5500. Well, visuals, the ATI stomps all over the V5. But, if you play mostly simulation games, or those w/out FPS demands, then the V5 maybe for you. The V5 provides the best FSAA out of the current batch of cards... 2x and 4x... But, if you play games such as Quake III, you probably should go with one of the above or better. The V5 isn't much sadly, plus who knows with the support you'll get in the future.
Stick with one of the above, unless your games are limited to Simulation style.