I have an Xbox and can't recommend it enough. Played on a few PS2s and the Xbox blows it away in terms of performance.
Best gaming experience - Connecting it to a receiver with a digital AV cable and playing Halo in 5.1 surround. Glorious!
(only 3 weeks until Halo 2 hits British shores... I just know I'm not gonna get any work done in November!!)