I picked up the same card a couple of months ago, and have had zero issues with it using this modded set (which will work with any Xonar), ASUS XONAR Unified Drivers 1.64 (post periodically updated) « brainbit
I also never bothered with the driver
disk (makers a nice coaster) as I knew about problems with the driver on it from other forums.
If Windows has a hard time detecting the card, wouldn't it not even display the card in the device manager?
It is being detected, it is the "Multimedia Audio Controller" that you are seeing in Device Manager.