They should be able to use XP Media Center I would think though you'd have to call them to see if this is possible to do on a custom laptop. I think it should be possible though it may take a few calls and some patience since most of the pre-built systems will have Vista now. Another idea would be to go to those Outlet stores that sell systems as they may have such systems, e.g. here in Calgary, AB there is Laptop Depot, Computer Outlet, and ComputerTrends to name a few examples where I see ads for laptops with XP Media Center on them.
As expected, there's a lot of hype about Vista. Personally, I don't think I need or want Vista. Unfortunately, all the laptops I've looked at come with Vista pre-installed. Anyone want to tell me why I should be happy to receive a laptop with the "upgraded" operating system. Pre-Vista it seemed that Windows Media Center was well received. Any chance of getting Media Center instead of Vista pre-installed on a new laptop?