Right now I use:
Zalman ZM-RS6F 5.1 channel headphoneshttp://www.directron.com/zmrs6f.html
They're only 45.99
They've been great headphones. There are certain games where I've actually gotten better simply because I can hear more accurately where things are coming from.
That's actually the same site I ordered them from, and though I paid for 3 day shipping I received them in the evening of the next day. YMMV on the shipping, but I've heard no complaints from others who've ordered there before.
And my soundcard is a Soundblaster Audigy 2 ZS, which can be had for about $70 to $85 or so at places like Newegg.com.
A lot of people bash the audigy and/or it's drivers, but I've had nothing but an excellent experience with mine. It sounds great, and rocks for gaming.
Quick picture of the headphones on my desktop next to my router, and another headset, to give you an idea of how big they are: