Yea i would get the 360. The wii and 360 are totally different systems and you almost need both. That way you have the fun games with the great controls in the wii, and then you get the great graphics and some 'hardcore' gamer games with the 360.
PS2 without a doubt. great, free online and it's got the best game library out there. their still making games for it too. cube is out of the question. but if you love halo get an xbox or an xbox 360 (id say xbox since it's so cheap) live is also really good. and theres a big game selection for xbox too.
Probably the 360, until Gran Turismo comes out I don't think the PS3 is worth buying, especially at the price it is at. Or you could wait until after Christmas and see how much the PS3 is and what games are out.
Either an Xbox 360 or a PSP. The only thing is, Xbox 360 you have to pay for online which is a rip off. I have a PSP and am loving it. MOHH is awesome online, and so is SOCOM Fireteam Bravo II. There are pretty good games for both however.