Turtle Beach used to build a good card. They stopped designing cards a few years ago and only offer repackaged sound chips, from other companies, on a card.
M-Audio boards have lousy, to abysmal, DirectX Sound (DirectSound) support, so they suck for gaming. They do provide the best quality of sound for other standard Windows stuff (ASIO, WAV, ....).
The Creative Audigy 2 and Audigy 2 ZS lines are probably the best, most stable sound cards Creative has ever shipped. The X-Fi line is coming along.
Not a big fan of Creative Labs, but they are the only sound card company left on the market actually making sound cards which can actually provide a better game experience through lower CPU usage, and better quality of sound.
Just avoid using them with VIA chipset motherboards. Or, at least, the older VIA chipset motherboards as VIA really had some compatibility issues.