Have you looked into this thing?
You'll still probably get a bit of noise due to it being omnidirectional, but the sensitivity distance rolloff is probably large enough to make it insignificant compared to a desktop mic.
+1 on the Antlion modmic.
I used the Zalman for a while, and it was borderline acceptable. The Antlion modmic is much better. In fact, I was surprised how long it took me to find it initially, because it seems like an obvious choice.
I don't remember what I paid for it (maybe $25), and I see Amazon is out of stock, but it's far better. I'm not suggesting it will replace a good Shure mic for recording music, but it's far far better than the Zalman for headset use. Speech is much clearer. On skype it's far better than cellphone quality, and the magnet it uses means that if you bump it you won't just break it off. You can also easily adjust the boom for your needs, and rotate the whole thing out of the way for when you aren't using it. Highly recommended.
In fact, you can just have my Zalman, if I remember where I put it. It was immediately relegated to sitting in a box after I picked up the modmic.