Is it possible to record HD video w/ an external webcam?

I bought this Logitech USB webcam specifically because the product description said it could record 720p video. That was over three years ago, and to this day I've still never been able to record 720p video on a Mac with this thing. I've done a lot of googling about it, and I keep finding finding instructions on how to use Quicktime to record video from a webcam, but the problem is that Quicktime only gives me these three format options: 320x240, 640x480, or 1600x1200! That last one is so big that if I try to use it, my computer is only able to capture a few frames a second. I've tried other software, like Debut, but I just have the same problem.

The thing is, I know this thing can record 720p video, because I've tried it on a PC, and it did it no problem. It ships with Windows software, but it's supposed to work on Mac or PC. I guess I just assumed that it didn't need any software on a Mac. Since I don't own a PC, I finally broke down this evening and tried to install Windows on my computer with Boot Camp. But I had all kinds of problems and I finally gave up.

I'm guessing maybe I just bought the wrong webcam. So, if nothing else, perhaps someone could suggest a different webcam for me to buy? One that can record HD video on a Mac?

Thanks.