Have you uninstalled all the ASUS related software including drivers and any other included extras?
The thing about USB headsets is that they contain a soundcard, so even without any other sound devices in the system, it should work. However, anything attempting to manipulate audio could still cause issues, which is why you should make sure you've cleaned up after the ASUS installer.
Somewhat offtopic, I've had horrid experiences with both ASUS and Creative soundcards/drivers:
My old ASUS card would crash randomly and repeat the last half second or so of whatever was playing infinitely.
My current built-in Creative "sound card"(which does portions in software) tends to crash in a way that turns up the volume to maximum, and won't let windows control it; Wonderful when that happens
Creative drivers in general are usually unstable, from what I've read, so look up some reviews before you consider buying from them(should've followed my own advice on that
).