I have a 360 and a Wii at home and I can say I'm considering getting a PS3 for the Blu-Ray, but I can't seem to find many compelling unique games to buy that aren't on 360 or on Wii. On top of that, I'm not that big of a movie buff and so PS3 is a nice thing to have, but it's not a must-have.
I like the 360 the best of the two. For me, it's always been about the game lineup on that platform. '07 was a knockout year for 360 games and I'm still quite hooked to Halo 3, Call of Duty 4, Mass Effect, Virtua Fighter 5, and Bioshock while I'm also anticipating Turok, GTA4, and Devil May Cry. The arcade games are great when you need a breather from the more "serious" games. I have Xbox Live Gold, but don't see it as a massive value even if you're just an avid gamer, but not an absolute hardcore one; I tend to fall in the former category. I just have money to waste, that's all.
On a side note, I wouldn't overpay for an Elite unless I knew for sure I was going to max it out with downloadable mods and other arcade games (thus the 80GB HD) and the cooling system for the newer 360's (mid-Summer '07 and onward) is pretty good. I bought one in September for my birthday and I've yet to encounter any problems.
I'm with ACS in saying that PC is still the best gaming platform in my opinion, but I'd rather use it for my programming and design needs.