With my SuperMicro P6DBS, USB worked with 2031, 2072 and 2099 right away. Make sure you have USB enabled in the BIOS, and you've got the latest BIOS revision for your mobo.
You could also give us a little more info, like what mobo, BIOS revision, USB devices, and NT build you're actually using...otherwise you might just get people saying "well, it works for me"