[johnmeyer]

Whatever differences you are hearing, they are not directly the result of running Linux or Windows. Instead, the "quality" is most likely the result of both the application (media player) you are using, as well as the settings you have created in the sound card driver. There are a huge number of settings that you can change, and without any information on the settings you are using, it is impossible to answer your question.

In Windows, you go to the Control Panel, find the applet for your audio driver or sound card, and change the settings. For my Creative Labs Ensoniq card, in Windows, I have at least six tabs in the dialog box which controls the sound card, and each tab has at least half a dozen settings. Many of these completely and totally change the nature of the sound which, depending on your tastes, would make the audio sound "better" or "worse."

You then find the "Options" or "Preferences" dialog for your media player, and look at the settings there especially, as others have already said, at the EQ settings.

So, if you can be more precise about what the differences are (is there more treble, or more bass, for instance), and describe specifically why you like one vs. the other, you might get some more replies.