I bought a X-FI music about 4 months ago and found that it made a suprising difference
The catalyst was a good value set of Logitech Z5500's from BlackDwarf, and the 2 in unison sound great, even with music. I particularily like the 'Crystal' processing on the X-FI makes poor MP3s sound like they have some depth.
Oh and cranked up BF2 sounds the nuts.