I had an XBOX 360 up until about 2 weeks ago, which I sold on CP here. The reason I sold it, and all the games I had, was to pick up a PS3.
The main reason for me is that for the most part, I only play sports games, so I really wasn't using the XBOX. I enjoyed gutiar hero, and some of the niche games, but for the most part... demos got boring, and my HD-DVD drive became obsolete.
As a movie-file, the fact that the PS3 is a Blu-Ray player was a big deal to me. Had HD-DVD won the format war, I'd probably still have the XBOX. Down time between sports games are now filled with movies.
Game play, and online experience, you're probably going to find that it's the same.
One of the other benifits is that the PS3 was much easier to make into a media centre than the XBOX. I can copy music, pictures, movies, etc onto the hard drive. For the life of me, I could not find how to copy... streaming was the only way to make the XBOX media options make sense. I stressed over conversion, and streaming programs, etc.
As a former XBOX owner, I say I'm more than happy with my PS3. If I were to reccomend one over the other, PS3 would be it. I'm also using wireless, so I made sure the unit I purchased had the built in wireless adapter.
Hope that helps.
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