I bought an Xbox a few months ago, reluctantly.
I say reluctantly because I'm a bit of a snob about console games. Most of them seem to have sci-fi themes, which leave me cold, and the others are weighted heavily to sports titles and first-person shooters, at which, frankly, I suck. I prefer more meditative fare like Civilization, or chess or Railroad Tycoon (or the best wargame by far I've ever played, Combat Mission). You don't need a lot of computing and video horsepower to run them.
However, my PC is pushing the bottom end of the envelope per speed and memory when it comes to newer games. It's still fine, though, for most of what I use my computer for -- email, Internet, blogging, small programming projects, etc.
So which makes more sense? To spend $1000+ every couple of years to upgrade the computer or $300 for a new console with $700 left over to buy games?
Actually I wish Microsoft would come out with $700 worth of racing/rally titles. Barrelling through twisty vistas on a 30-inch TV in a darkened room with force feedback is quite immersive. Toss in a minor buzz and it's also as much fun as you can have with your pants on.