Erm....look in my signature for my solution.
I use a MacMini, with dualboot (via bootcamp) WinXP, and it boots fast, runs real well, mine's a core duo 1.83gig setup.
Small footprint, easy to setup/install/use, great little box
IMHO the best for a decent CarPuter.
Should have bought mine before everything else!
Good luck with your setup.