Better off going for IP webcam rather than USB webcam IMO.
I use two Foscam FI8910W which have loads of integrated features, others on here recommend the ANNKE Sparkle 1 H.264 HD. Easy to setup, the Annke I think is probably a better bet due to being slightly easier to setup and on paper is higher quality, although I've never compared to know.
If you don't require rotate feature I've read some good reviews of
these - I'm going to fit one in my shed at some point and another in the entrance area of my house.