I've got both, and can guarantee two things: if you have the money (or friends with copies of games) to get your hands on the good stuff, it's absolutely worth having both. There are enough exclusive games or exclusive content that the only way to really get everything you can out of gaming is to own both. However, don't expect to use both equally--if you've had your Xbox longer, you'll still use that more (not that you won't use the PS3).