In addition to the OS choice, the KT400 boards seem to be having trouble running PC3200 @ 400MHz in more than one slot. Like mentioned earlier, a Win9x OS isn't designed to work with anything above 512, and really it's not that great above 256 megs.
I'd strongly advise going to another OS. ME is really one of the crappiest products I've ever used, and the reason I switched to running Win2k, although I run XP currently.

With the Audigy, Creative has some driver updates you might wanna snag. Do know that you'll still have to install the drivers that come with the card first before updating (which I think is really stupid).