I have a Icemat Siberia (now steelseries siberia) headset which cost me about 45 bucks. Comes with a clip on direcitonal mic and lets me rock people nicely in CS:S and TF2. Not to toot my own horn, but I am the #1 player in both total kills and kills/minute in TF2 on the server I play (its pretty competitive too), and I definitely attribute a bit of a boost in score using the headset over my speakers since I can detect directional footsteps and whatnot much more precisely, so I can vouch for your needs with it well enough.
However I am considering replacing my headset with a Sennheiser 555 and keeping the microphone that came with the steelseries. Still I would recommend the headset if you arent an audiophile at heart.
The Razer I hear good things about, and the 5.1 nature of the headset intrigues me over just the stereo headset, but I honestly wonder how well it works. Not to metion, the Razer card I dont hear such good things about without its headset and definitely the complaint is always that it is overpriced for what it does.