I would also have to give the nod to the ATI TV Wonder over any of the Hauppauge cards. I have had them both and the ATI TV Wonder is better in terms of everything - quality, capturing, features, etc.
However, there are only beta Win2K drivers available and from what I hear, they do not work very well. My only gripe with ATI is that their driver support sucks. This goes for the Radeon to the TV Wonder. I am perfectly happy with my setup on Win98SE, but I will say that this was the only piece of hardware not supported when I was dual booting Win2K. I probably would have made a complete switch if it was supported and gaming was a bit better in Win2K.
As far as Hauppauge, they update their software and drivers too much. At first I thought it was cool, but I quickly realized that it was to fix bugs and most of the time new ones were introduced. Their card(401) kept crashing and their support sucks. ATI always answers their phone and the techs are very knowledgeable. They helped me with some advanced mpeg capturing questions. Too bad they do not put more effort into driver development.
I have heard good things about the newer 3dfx tuners, may want to check out their Win2K support.
LJ