Doctor Milkshake
The game looks great from what i've seen, but i don't think it's worth buying a PS3 just to play it.

I already own an 360 and a Wii and i'd feal like a complete jerk if I owned all three.
I agree with Evalad in that it's a privilege,,, But you could always sell your Xbox!

As a long standing fan of the series I'm giving MGS4 a massive 10/10.