You're doing all of that music on your PC a disservice by attempting to filter sound through those coin-sized built-in fakers. A proper set of speakers won't set you back a month's rent and will have you rocking until the cops show up. If desktop real estate is no object, you can't do better than M-Audio's Studiophile AV 40s.
Think monster floor speakers trapped inside tabletop bodies. These units aren't as compact as standard desk audio counterparts, but what they take up in size, they make up for with sound. Highs are crisp, and distortion-free bass notes rattle your bones. Watching movies and television from your PC suddenly becomes more enticing and worthwhile.
Fancy yourself a recording artist? A pair of quarter-inch inputs lets you connect the AV 40s to a mixing board and use them as studio monitors. Try blasting some Journey "Faithfully" on these. You won't regret it.