Why do Sony consoles last so long? They have a lifespan of about 10 years, which is more than double that of other consoles.
In my time I have bought a Dreamcast, XBox and Gamecube and none of them have lasted for very long at all, mainly because none of them did so well, but that's not the point. Amazingly enough I've never been interested in the Playstation consoles, and recently sold traded in my PSP for a DS as I felt it wasn't doing so well (and I had many more games for the DS anyway).
Maybe I've just been really unlucky in my choices, but it has really put me off games consoles, yet always they manage to entice me whenever the new ones come out.
Now that the XBox 360 and the Wii are out, they both have some excellent games on them which I am very eager to try, but the thought those will be the only games I'll get to play on them for that money is what puts me off.
I could always wait until the next generation after this comes out, then buy them when they are at their cheapest (or in the case of the xbox games, just wait until they come out on the PC). Its a hard choice to make.