Help Me Upgrade My PC Soundsystem

Can anyone recommend a good, affordable set of speakers for use with a PC? I’m not actually sure how important the speakers are vs. the soundcard, but my system currently doesn’t have much power to it—I can’t turn it up very loud, videos in particular are generally too quiet for me, even at max volume. I don’t often listen to music on my computer (I usually use my iPod, since iTunes causes my whole system to crawl if I try to play music with it), but I do occasionally listen to Pandora or an artist’s MySpace songs, etc. and I find that I can’t turn it up as loud as I’d like.

I can’t really tell what my current sound card is, it just says Creative SB Live Series (WDM), but I’m not sure if that’s a full description. My speakers are like $20 cheapies picked up at Office Depot.

So…any ideas what’s the best option for an upgrade here?