My integrated Realtek HD Audio sounds like anything but crap. Sounds pretty good actually. I have an M-Audio card in another system that I use as part of my setup for transferring old LP's to CD, VHS tapes to DVD, etc, etc, etc....and the Realtek sounds every bit as good as the M-Audio. Only difference is the volume levels are slightly lower on the Realtek. No big deal really.
And yes I have a good speaker setup on both systems.
Anyway, I am running Vista on both machines and have yet to have any issues with either sound solution.