How do I turn my imac into a media center?

What do I need to buy to be able to watch/record tv on my imac? I would also like to use the imac to record tv from my 42" LCD tv in my bedroom which is in the next room over.

Thanks,
Joe

you may want to get a usb tuner
let me suggest something from eyeTv: http://www.elgato.com/elgato/na/mainmenu/products.en.html