Kirk has me babysitting his Xbox 360 since he's too busy to use it, so I've been renting a few games and trying it out. It's definitely a giant leap forward from my Gamecube in terms of graphics/sound. It's a bit like getting to 'play' a movie. For any sports nut, NHL 2007 from EA is amazing for the 360. I just rented Gears of War and had also rented NBA Street Homecourt (Amazingly detailed graphics with a great storyline to play along to - a great game to play with a bunch of people). The system is lots of fun and the ability to play online is a great option, though I can't take part without a paid Xbox Live membership. Having the ability to download demos of games and be able to try out the first few levels is nice as well, especially since Blockbuster charges $10/week for a game rental now.
To show how geeky I really am, you can check out my Xbox gamer tag and all my "achievements." Seriously. I eat this stuff up. Horribly geek and terribly fun.