I have both. I purchase an xbox 360 a couple years ago and from day 1 it didn't work properly. I said screw it and bought a PS3. I've never had any problems with the PS3. PSN is free, which is a huge advantage and the graphics are better.
People complain that xbox live is more popular than PSN, but I have never had any trouble getting any game going on PSN. If I were you, I would go with the PS3. It is far more worth it than xbox. If you do go with PS3, give me your username. Mine is Miami_Dolphins34.