Im basically running the same thing you are:
Radeon 32DDR, Win2K sp2, and the new 3276 driver.
Custom resolutions work, except for interlaced resolutions. I did get interlaced resolutions to work for the desktop only, with the previous official 3201's (I think thats the driver number). DVD playback however, did not work, as only the upper 2/3 of the image displayed. The "refresh custom timing" binding did not help much, as the image would keep reverting back to the 2/3 mode after a second or two.
You're gonna have to get the registry keys to unhide the custome resolutions, and to unlock custome resolutions as well. Check here:
http://www.dtvmax.com/radeon_guide.htm
Good luck!
-Ryan Dinan