Get the Chaintech AV-710 everyone loves. It's $23.50 at newegg, and offers the best audio you'll get short of spending ~$100. As for the importance of components, both matter. Crappy speakers on a great soundcard will sound terrible, as will great speakers on a crappy soundcard. The Chaintech AV-710 will wring every bit of potential out of anything in your price range, however. With your budget, it's important to concentrate on the speakers.
Have you considered going with headphones instead of speakers? For about $175, you can get much better quality all around from headphones. I'd suggest looking to see if you can find a deal on the Sennheiser HD-595 headphones, if not, get the HD-590s.
If you're determined to stay with speakers, someone else can probably provide better recommendations on models than I can.
