A few reasons that are easily (*cough*) overlooked:
1) The selection of games is different; some games that are coming out for Gamecube, for instance, are not coming out for PC. Thus, I will buy a Gamecube when the time comes.
b) My computer sucks; it's obsolete by 4 years.

I don't have the money to overhaul my computer
5) I don't have the money to buy a new computer (they cost more, you see). True, the basic systems are getting cheaper, but if I'm going to buy a new computer, I'm going to buy a DAMN GOOD new computer
x) Consoles usually do not require big upgrades to play the latest games
18) I like some console games better than computer games
20) The face-to-face multiplayer, i.e. not everyone has to have separate, compatible machines; you can plan together which, goshdangit, is just plain fun
v) Consoles are getting relatively cheap
49x) Consoles are evolving, and I personally am starting to become impressed
zz) It's easy to take a console with you; ya just need to find a TV
100,00) Consoles fuck up a lot less than computers (for me), and I tend not to get frustrated with them as easily.
NYAH!