Looking for a HD Webcam for Skype

I've been turned off from buying a new webcam for Skype for a long time now, because I can never really tell if a particular "HD Webcam" will actually be HD in Skype. I know that initially, Skype required the camera itself to be capable of hardware encoding the video, and would not allow the camera to offload that task to the CPU.

Since I started looking again, I can't find any source of definitive information on whether or not a particular webcam will work properly with Skype in HD, so I come here. I'm looking at models mostly from Logitech and Microsoft in the $25-50 range, and would appreciate some advice.

Requirements:

  1. I do not need it to have a microphone. I have a very high quality audio setup right now, and intend to use that, though of course, I wouldn't turn down a camera because it has a microphone. It just shouldn't factor into a reason to buy that model.
  2. It must have the ability to mount to a full size (not laptop) monitor

My current front runners are:

The Logitech C270 ($28) at the lower end of my budget, and the Microsoft LifeCam Studio 1080P ($45) at the upper end.