I hope I don't offend anyone, but I've always been a Nintendo fan, so I'm definitely skewed in that direction. I don't know if that makes me a fanboy or not, but I think I can reasonably justify never considering an Xbox - it seems like all the best games also come out for the PC. On my computer, I've played Halo, Doom 3, SW: KOTOR, SW: Battlefront, MGS2: Substance, Silent Hill 2: Director's Cut, my brother has ES III: Morrowind...there are quite a few others, I'm sure, that I could get for the PC if I really wanted to. Like, Fable's kind of on my radar.
Learn what EXCLUSIVES are, Microsoft. Geez... I know not everyone has a decent PC, but I do, and because of that, an Xbox seems mostly redundant.
I might be interested in the Tecmo games, like Ninja Gaiden (since I liked the original NES games), or DoA:XBV (but that wouldn't be for "gameplay" reasons, I'll admit that right now). And perhaps a couple other real exclusives, but a handful of games isn't enough for me to consider it.
It sounds like the Xbox 360 library is going to be the same. There are some Rare-developed games like Perfect Dark Zero and Kameo that we all thought were going to be for the GameCube...if they remain true Xbox 360 exclusives, and even if I could say I really wanted to play them, a couple games is still not enough.
However, there is that Xbox 360 controller for the PC...is that any good? I've been using an N64 controller on my computer for YEARS. I don't know if I'd replace it soon, but unlike the original Xbox controller, would you say the X360 controller is worth checking out? (That seems like it means giving an Xbox 360 experience to those who prefer those same games on the PC like I do, which I'm thinking emphasizes the redundancy, IMO...)