Your MacBook Pro has a built-in webcam, also does every other Mac except the Mac mini and Mac Pro since 2006 have one, thus the camera you buy for that Windows laptop does not need to be compatible with Mac OS X, only with Windows and Skype.
What exact Windows PC do you have?
Since 1600 x 1200 is more than 1280 x 720, yes it is HD, but since it has no reviews and ratings, it might be better to keep your hands off from that one.
Maybe have a look at the Logitech ones.
PS: Why does it need to be HD, which is much more CPU intensive than non-HD cameras?
The Logitech models are high-definition. I find the Logitech cameras to be excellent. I think the model number c 9100 is actually 1080p. I would look on the Logitech website for more information. Good luck.