mine *barely* works under XP. I say this as I have NO support for 5.1 and the rear out doesn't seem to work with the DTT2500 speakers...
I'm interested in switching too. I bought an Audigy and I thought it was terrible. I mean, you have to install 500 apps to get any functionality, and I couldn't even get the damn thing to be recognized by PowerDVD as supporting real Dolby Digital, just some emulation 6.1 dolby surround or something.