I have the ASUS P3VX4 and have had NO problems at all with it and WIN2k. The ATA66 side of things is simple emough. You use an ATA66 IDE cable plug it inot an ATA66 compat Hard drive.... and guess what it works. No need to do anything else at all. That simple..
Im running this board with
128MB PC133 SDRAM
ASUS AGP-V6800 Pure DDR (running 3.78 and 4x AGP perfectly)
Pentium III 600E running at 800Mhz.
WD 20.4GB ATA66 Hard Disk.
VERDICT: AWSOME.
Enjoy your new board.