I also have 1 of the usb 4channel ones and it works good, has motion sensing capabilities, it came from geeks.com also, the only draw backs are camera adjustments pertain to all 4 cameras at once, no individual adjustment for each camera, and with the detection of motion it will email you a snapshot of the camera.
I also have one from china that is called a easycap004, very similar name but is a box about the size of a window/door sensor with 4 video 2 audio and a usb cable to attach to computer, this uses a different software only compatible with this device, each camera independant settings for each camera, motion selection for certain areas of the screen and when motion detected it records video, not snapshot. More features, but demanding for computer system,
Finally went with the 4camera dvr system from Harbor Freight (made in china also), so far has been working great, 4 channel record 60fps, you choose adjustment, i am doing 15fps per camera, full color in day, very sensitive night vision, nice system for the price. Decided that a demanding system needed to be seperate from computer and also have the features that i needed and this has done that.
1 last thing and i think this is important, both devices claim to work on vista and they dont and no support or update available. Geeks.com claims vista but incorrect, be careful. Of course not their fault, the package is what claims it not them.