If your planning to go online I heard that XBL has the better looking interface for the xbox 360 which is a real plus. Not to mention it supperts HDMI so your going to get a fully clear picture.
Not to mention that XBOX 360 has alot of games you might enjoy. But some games are on the PS3 as well like GTA IV and COD 4. But 360 members get new DL content on the daily. I can't say the same for the PS3.
Not to mention.....you'll have to pay 50 bucks for a year. Or you can pay 20 for 6 months or 7 bucks for 1 month just to try it out.
I dont have XBL but im happy with my choice. Happy gaming. Peace!