Full HD has to be decoded by the graphic card, 720p can be decoded by software, the USB device is fast enough for transferring the full HD Channels from the device to the computer.
There have been USB 1.1 devices out there from another company which supported DVB-C but due the speed limitation (12 mbit for USB 1.1) it's impossible to watch HDTV channels with such devices. The Sundtek MediaTV Pro requires USB 2.0 and is fast enough for this.
