Pros: Best video capabilities available to the low-end consumer
Cons: Sound capture could use some improvement, helplessly poor software
The bottom line: If you want high quality video for a great price, this is the webcam for you. You will find nothing better.
I own three Logitech QuickCam Pro 4000's and love each of them.

The QuickCam Pro 4000 is the dream of anyone who wants to teleconference or run a live Webcam. The Pro 4000 is capable of displaying an image quality of up to 1 MP at 50 frames per second. This translates to real-time video capture and transmission for any need you may have. This means you will no longer have choppy or pixelated video, only crisp fluid motion.

The audio is a different story. While ACCEPTABLE, the built in microphone is nothing more. The microphone has a very limited range for clarity (within ~ 1 ft. to 4 ft.) and anything outside that range becomes blurred or jumbled. Background noise renders any audio transmission completely impossible because the Pro 4000's microphone picks anything and everything up.

If you want to talk, get a $10 microphone, dont use the built in one.

The software that comes bundled with the QuickCam Pro 4000 is absolutely terrible. Do not even bother installing it. It has a very limited number of options and does not support broadcasting video from anything but Logitech's partner site.

Use WebcamXP with the Pro 4000 and skip the hassle of trying to figure out software that will be useless in the end anyway.