We are over looking one small factor. How long has sony been in the gaming/entertainment business (games, consoles and such)? How long has Microsoft been in the same business. I know they are competiting directly but Sony has a few iterations on Micrsoft, not to mention thier entire business is based around designing electronics.
I'm not saying Microsoft doesn't try and design electronics also, but thier core competency has been Operating systems and software for a long time. The Xbox 360, as well as the Xbox, are designed to craft a reputation and build up a base market. The long term goal with the Xbox line is to create an all in one entertainment system that fully itegrates with periphrials and Windows PC's.
Last time I checked that wasn't Sony's overall goal, though they are starting to steer in that direction. Microsoft has more of a long term goal with the Xbox line than to just overpower Sony. Sony makes a good console but I was never comfratable with the controller, it was too small for me. Each console has its strengths and weakness, I mean who can compare with Halo (lets not argue that here).
Trying to determine a winner is damned near impossible, because even with the superior hardware if no programmer cant utilize it because its so complex then you've wasted your time and effort.