I have the newest 3056 drivers from the net... haven't even bothered with the original drivers, so couldn't tell you which ones are better, but these ones work for me...
I have dual-boot, between WinME & Win2000 with my ATI AIW Radeon.
I get better 3dmarks scores in WinME, by about 300... furthermore, it is not evenly distributed: In low resolutions, Win2000 actually has better framerates (when processor is the limiter, presumably). In the higher resolution/detail, when the card is the limiter, FPS is much lower in Win2000 than in WinME, presumably because Win2k is still oriented toward business and its graphics support isn't as great. So although it averages out to only 300 points difference, if you like playing your games in high-res, WinME/SE might be a better idea.
The Win2k is more stable though, and it may be just a glitch on my machine that's making it run slower -- most of similar glitches are... Plus, this is just an artificial benchmark test, games actually run fine on Win2k
eagerly awaiting hobbit's post (though he slowed down recently