This is all going to be a bit random as I try to recall the bits I actually want to respond to.
-- Xbox's architecture is
very much PC-based, but it does away with the major problems (e.g. having to deal with a big clunky OS, bad drivers, and different hardware configurations) that normally plague PC developers, so it's far better than an equivalently specced PC.
-- I don't find any of Xbox's current library particularly compelling. About the only Xbox thing I'm really keen on seeing is neat homebrew stuff. PS2's library runs circles around Xbox's. Someone mentioned support from Konami and Capcom for Xbox, but so far it's little more than ports (Air Force Delta Storm, MGS2 Substance, Genma Onimusha). As far as I can tell, Konami has announced exactly zero original Xbox-exclusive titles, and Capcom only one (Tekki/Steel Battalion). Ports do not make a successful system.
-- I can't stand the US Xbox controller. The stupid thing looks like it's designed to be stared at rather than used. Thankfully, there's a nice little gadget from the magical Far East Lands that allows the use of other controllers...
-- Microsoft, Sony, and Nintendo have all done incredibly stupid stuff at some point, so you might as well not buy any of the new consoles if you're not willing to buy from companies that have messed with their customers.