I got a Logitech C310 for one of my Windows 7 desktops. Everyone I Skype with says it's more clear than any other person they Skype with. One person said it's so clear, they feel like I'm in the room with them. I always get compliments with this thing from the other end of the call. I would have never expected to get a compliment from a webcam!?
It's easy to setup and I'd recommend downloading the software for it from the Logitech web site since it's the latest release.
The camera is capable of 720p video and has decent still frame capture capabilities. It runs around $50, but I got mine on sale at the double-B for $30:http://www.newegg.com/Product/Product.aspx?Item=N82E16826104368&cm_re=c310-_-26-104-368-_-Product