Should I buy an xBox 360 or PS3?

Hey, I'm 16, and for all my life I've been raised on Nintendo. Finally my parents have been coaxed into buying me a system of my choice. Nintendo GameCube and Wii were great for Brawl and Sonic games, but I'm primarily into sports now. Madden, NCAA Football/Basketball, etc. I don't know much about PS3 or xBox, but I was wondering which one I should get if I got almost primarily sports games? Any advice would be great.