SoundBlaster Live! sound cards come complete with two main (front and surrounds) outputs, mic input, line input, and SP/DIF output. Some support 5.1, I think that they all have a Dolby Digital 4/6 speaker decoder onboard. They have about 2MB of RAM for MIDI instruments, and the software package supports sampling WAV clips for synthesized playback. The drivers are available on CD or on Creative's website.
Well, I bought a SoundBlaster Live! Value at a computer shop for $40, and it's about the best sound card I've ever used. It's supported by every operating system I've used, and it's got great surround sound. I play Half-Life, and I can hear boxes crumbling behind me, and life is sweet. If I had $200 to fork over for the better model, I would. Otherwise, the Value is enough. I usually don't buy generic, because I have found too many generic parts fail, and generally Creative is the best in audio for the computer, with Aureal a close second.
About the nVidia vs. 3DFX thing, I think that 3DFX cards are nice, and have a lot of cool sounding features that mostly have no affectation other than sounding cool. Full Frame Anti Aliasing? Great if you're running at 320x240, where the frames are so small that it takes less than 5MB to render, but at 1024x768, 32BPP, I don't really care too much if the lines are jagged, as long as I can see the guy I'm trying to frag at a decent framerate. nVidia cards do great work, great framerates, as long as you can find drivers for them...