Any Reason I should? Honestly I don't know a lot about vCards, it's not that I really use the ones I have. I game but I'm not into FPS, no Crysis, Far Cry 2 or anything that demanding. Mostly just strategy games, football manager, and rpgs.
I compared different models from the ATI 5000 series. The 5850's usually run a hundred dollars more than the 5830's. The 5850 is a jump from 1120 to 1440 stream processors but that hardly seems worth a C note.
NVIDIA is similarly priced but doesn't look like there's a lot of difference between the two. They use 'processor cores' (a lot fewer than NVIDIA's) 'stream processors' I have no clue what, if any, difference there is between the two.
Here's one of each in comparison