Microphone/headphones/headset solution (gaming)

I recently obtained a high-end creative Xfi sound card for a nice price, and after (thus far) ascertaining that there's no way to get the pretty usb headset I'd been considering to mate with it, I'm in the market for an analog set.

However, I'm still considering getting the usb headset for LAN and skype as if I must go analog I'd rather get a good pair of headphones than a mediocre headset. I'm looking at getting the Sennheiser HD 598.

I don't want to have optimal sound quality for just single player as I mostly game online, so I'd like some suggestions on finding a cllip-on mic.
I'd prefer to have something with decent noise cancelling e.g. able to deal with my typing, person in the background and my static breathing.

If this mic is so good it will eliminate any need or want for the usb headset, then I'm willing to pay up to £80-£90, which is the range that headset retails in. Not that I think a consumer mic for my purposes will cost that much, but just putting it out there on the off-chance someone suggests a £500 studio mic!

I don't mind if it's not a particularly dainty mic, but I don't want a desktop mic; I want something for use in conjunction with the headphones I mentioned.

I may be looking for something that doesn't exist, in which case a next best alternative would be appreciated. With that sai my experience with desktop mics hasn't been favourable and they feel restrictive.

Thanks in advance for any replies.

This could all go to <self-filtered> when I'm informed I suck and my sound card can provide output to a usb headset. If that happens, I'll probably want an analog headphone set later anyway, so I'd still be interested in a response to my original question.