I plan on sticking with a pc, but I'll withhold my judgement until I actually try out the xbox360 (the ps3 is a way off, but I'm getting either a better pc or xbox within the next couple months). Here are some thoughts I had while reading through this thread:
I play first person shooters more than anything, but I hate using controllers. If I can't use a mouse and keyboard with the xbox360 (it should be possible because the 360 uses USB ports) then I probably won't get one.
I also like the fact that computer games can have mods. I quickly got bored with Halo (the original, the second one sucked IMO), I still continue to play mods for HL2 long after getting bored with the campaign and multiplayer.
I remember that one of the big selling points for the original xbox, at least for me, was that it had a hard drive and you could get expansion packs for games. Where are they? I don't even know if expansion packs would be possible since the games aren't installed on the hdd.
In case anyone was wondering, I heard you can use the xbox360 cable controller with a computer because it uses a USB port.
A friend of mine had one of the xbox360 guides that talked about the hardware, the games, etc. IIRC, modified powermacs were sent to game developers because they were closest to the estimated power of the xbox360. Make of that what you will, I don't know what that implies about pc's catching up.