Not the greatest - the ones that come on the CD are pretty basic, I didn't stick with them too long as I got hold of the Beta version 2 drivers. The V1 drivers wouldn't let me play CD/MP3 through all 4 speakers, V2 do which is why I stick with them.
These give the same interface as Win9x and the functionality was fine/perfect until I did a complete reinstall of W2K last weekend. Now, the control panel applet is a little unstable when using/changing settings, and there's a smonitor.exe that monitors for when you plug headphones in and automatically turns off the speakers - this now Dr Watsons within 2 minutes of booting into Windows so when using headphones you have to manually turn down speaker volume. These seem to be the standard complaints for the V2 so I was just lucky before my reinstall
As far as games go, Quake seems the same as Win9x, UT isn't as good (seems to flick between giving full surround and stereo through 4 speakers and using the hardware accel. option cuts out some sounds completely), Serious Sam I have to play in DirectSound (which sounds pretty good) as the EAX option is too quiet and gives a very echo-y sound. Can't speak for other games as that's all the W2K gaming I do, everything else is in WinME.
If you've already got V1 installed, the uninstall utility doesn't, so I had to manually clean things up (but hey, we're Radeon users so we're used to that )
The beta install package is missing a midi synth bank, CWCDLS8.CLS. I copied the one off the CD to the install location.
Also, the inf file has two sections that refer to help files - all the foreign ones aren't there so will need to be deleted or commented out. The only help file in the install package is ENG.HLP.