I'd spend your money on an ATI Radeon 9700 Pro video card. For a sound card, the performance between the Hercules Game Theater and Creative Audigy Platnium is just about perfectly even, so pick the card with the features you like best.
I'll give you two suggestions for speakers. If you mostly use your speakers for games and movies, the Logitech Z-560 are really hard to beat. The Klipsch Pro Media 5.1 might be just a little better for movies, but not three-times-the-price better.
If you are a music lover, however, you'll probably notice the Logitech (and Klipsch) put out too much bass. My favorite music speakers for the PC (and what I'm using to listen to Miles Davis on as I write this) are the Monsoon MM2000 4.1 system. At $300 these aren't cheap, but they are very good.
BHD