the xfi was the worst £100 i have ever spent
the driver support was shambolic.
the xonar has been a dream. brilliant drivers, intuitive interface, uncomplicated software, neat features, better sound quality.
hard to argue really.
Damn, about 3 years ago when I got my X-Fi Platinum Fatal1ty Champion the sound was excellent so that is indeed high praise (driver support is indeed very poor), which is why I'll be getting an Asus.
You have to bear in mind that X-Fi is excellent audio quality for mainly gaming and 3D positioning, how would your Asus compare for gaming in this respect?