Do yourself a favor and hold out for the next generation of consoles. As pointed out in an earlier post, the Next X Box is supposed to be released in Q4 of 2005. PS3 is due sometime in Q1 of 2006.
Honestly, if you're really itching to own a console I'd reccomend buying a used one. The price tags of the current ones just don't justify it anymore.
About the games... PS2 has a better feeling controller and offers a more eclectic variety of games. People play this system I believe for the sports titles and series, e.g. Final Fantasy, Gran Turismo, Tekken, etc.
X Box has the better graphics and offers some games that are exclusively licensed to them, e.g. Halo, Project Gotham Racing, OddWorld, etc.
The one reason I'd own a gamecube is soley for Super Smash Brothers Melee!
Btw, because of these soon to be released gaming systems I'm really not interested in PSP. I'm saving that $250+ for the next generation. Good luck!