Which Radeon are you referring to?
If your referencing the original ATi Radeon 32MB DDR it comes clocked at 166/166DDR and performs somewhat below a GF2 GTS, and pretty closely to a GTS-V at stock clockspeeds.
VisionTek tends to have good 2D image quality, so ATi will likely only have a very slight edge there.
The Radeon board offers a somewhat more complete 3D feature set, and has better DVD playback capabilities. It also tends to have better TV-Out quality, if you get a Radeon board supporting TV-Out.
Radeon 32MB DDR can generally overclock to roughly 183/183DDR, and the GTS-V... well I've heard overclocking reports on it ranging from 200/158DDR on the low end, to a handful of people reporting up to 2250/200-205DDR at best. Most people seem to get a bit above regular GTS speeds though.... at least with the cards that use 5.5ns DDR RAM.
Overall, it depends what your using it for. If it's to be used solely for gaming I'd lean towards the GTS-V mostly due to a potential for good overclockability.
If your only doing a bit of gaming though, and spend time doing other tasks then I'd definitely go with the Radeon as it's a superior all around graphics card.
This is of course presuming your referencing the original Radeon 32MB DDR, which I got the impression from your previous thread. If your referencing a different ATi Radeon board then my opinion may change significantly.