I have a Microsoft VX-1000 camera from today, and I can tell you it's fantastic.
The CPU usage in 320x240, RGB24 0-3%. I'am very happy now with it cam.
I bought yesterday a Genius slim 321C, but take it back to the shop, because with IR led this cam not working. The IR filter not or only difficultly removable from the lens, because it have IR coating and the lens glued to the camera optic house, not such as in the Labtec webcams, where removable the lens from the house. Sorry for my bad english.
Cheers!