to Cable Forum
most decent computer systems, especially media based ones, should have a variety of audio and video connection ports, perhaps S-video, amongst others. Your going to need to play around with the cables, probably buying a lead (maplin.co.uk are a good place to look for variety of what is available) to convert scart at one end to s-video or separate RGB video and phono plugs at the other. Leads supplied with the media centre may then allow you to connect it all up.