My recommendation is the Turtle Beach Santa Cruz. It packs the best sound for the buck. If you can afford it, go for the Hercules GTXP. It has the same DSP as the Santa Cruz and has an outstanding breakout box with all the connectors you need to build home theater dream system. Either way, you're gunna get great sound.
I can't honestly recommend a SB card anymore, given their notable compatibility problems. This may have been fixed on the Audigy cards, but these are still overpriced as compared to the superior sounding Crystal DSP cards above.