That depends. Some sound cards have the option to run Dolby Pro Logic 2 which will convert Stereo music to 5.1, and rather cleverly too in my opinion.
If you don't have the sound card with the decoder to do that, Power DVD with full options has Dolby Pro logic 2 built in. Though, thats a bit awquad to run music with...still, great sound.
I want to get 'me hold of a set of Logitechs!