Have looked at the demo on the xbox 360....Looks impressive. My local Tesco's PC game section has shrunk to almost nothing, whilst the xbox and PS2 shelves are groaning.
Direct to Drive is a good safe source for downloading PC stuff if you don't mind not having the dvd:
And of course Amazon area good bet too. It does seem as though the bigger supermarkets are stocking fewer PC titles than they used to.
Not sure about Asda, as have not been able to drive recently, but this may be due to the download factor....I've got a few titles that way, and as long as you have unlimited fast broadband, and a good backup system it's ok.
Still like to have the box and manual myself though.