i have both a PS3 and xbox360 currently.
as a hardcore gamer, i will tell you that the PS3 is fuckin awesome and its a better system.
but as a casual gamer who doesnt want to spend more than he has to; the xbox is prbably a better fit for you fancy.
its easier to play, and more arcady (if thats what you want).
the PS3 is more like a computer IMO, and way more complicated (more for the nerds and freaks like myself).
PS3 is better, but dont get me wrong; i love my xbox and still play the crap out of it... i actually spent all saturday night at my buddy's house whooping his ass on it...
for what you're looking for, the xbox will do you fine.... you'll love it.