EyeTV
http://www.elgato.com/eyeTV/
It is a piece of hardware that plugs into the USB port to get the signal in and software to use it.
It comes in some flavors.
http://www.macmall.com/macmall/searc...=1&incimage=on
Also to RIP your DVDs to your HD and remove that annoying copy protection. (free)
http://www.versiontracker.com/dyn/mo...8599&vid=90308