Media centre advice? (Bye bye Foxtel)

I’m cancelling my Foxtel subscription. Foxtel = Murdoch+Packer+Telstra and I’m tired of giving them my money. I also don’t have as much time to watch TV as I used to. The only things that I watch on Foxtel these days that I wouldn’t be able to see on free to air are the 24 hour news channels (mainly Sky News and BBC World) occasional international cricket matches, and the Comedy Channel. For news, I can make do with ABC and SBS, the cricket I can live without (especially after the tedium of the World Cup) and for comedy there’s DVDs and downloads.

What I will miss is the iQ recorder, but as I’m about to buy a Macbook Pro, I reckon I might turn my old WinXP desktop PC* into a media center.

Do you have any recommendations for this? I’ll need a tuner/capture device and software – ideally cross-platform and open-source as eventually I’d like to convert the PC from XP to Linux (I’m going to test the waters first by converting my old Dell laptop to Ubuntu, and maybe experiment with Windows on the the Macbook Pro).

This is all new to me, and I’m confused by the options, so I’d appreciate any advice on how best to set up a media center PC.

* P4 2.8GHz, 1 GB RAM, 256MB ATI Radeon 9600, 3x 320GB HD, oh and a Canopus ADVC 100 video capture box, if that’s any help.