I use a sound blaster audigy and love it, it has EAX Advanced HD (essentially EAX3) and sounds great in the games that use it such as Jedi Knight 2, GTA3, SOF2 ect.
I'm planning on getting a audigy 2 sometime when the oem version is available, its supposedly even better.
They have the lowest cpu utilization rate of any sound card, esp the audigy 2 they've been improved upon quite a bit.
I've read enabling sound with an audigy is almost a lossless feature with an audigy while you take a rather large 5-15 fps hit on some other chips.
Also audigys have built in firewire, which i dont use but damn, its cool to at least have it.
If you prefer to stay away from creative as some have a bias against, I would recommend the turtle beach santa cruz.
Make sure if you get an audigy you are familiar with irqs and can get it on its own one.
good luck