I own all the current platforms and can point out a few things that you may not consider, but my basic advice is that the PS3 has much better longevity and features.
1. PS3 is extremely quiet, almost silent. The 360 is noisy like an airplane. This is a total deal breaker for me, particularly for movies. Perhaps they have improved the noise level since I bought mine shortly after the 360 launch...
2. PS3 comes standard with HDMI and 1080p support. You need to buy the elite 360 in order to get similar functionality.
3. PS3 comes standard with a Blu-Ray disc player, and Blu-Ray won the war.
Now, PS3 is starting to get some mature quality games but has a lot to catch up to 360's library. The 360 has a lot of good games, has a superior online interface and achievements. If you are highly into a multiplayer/competitive environment, you may wish to get a 360 or if you don't plan to utilize proper 1080p support in the near future.
Good luck with your choice!
