Do a search. There are at least a good dozen threads on this issue. IMHO, I'd lean towards the Radeon.
Drivers have iomproved to the point wherein you shouldnt have many issues. ATi's has shown marked speed increases with their last few driver sets. It's faster then the Ti200 in the vast majority of games, and has a better feature set. Better 2D, better DVD, better FSAA by default. Of course the HydraVision, and DVI is a nice addition too.
Only advantage to the GF3 Ti200 at this point is the better drivers, but from my impression ATi has been making solid strides in imporving them with their last couple driver releases.