mjoen,
Do you mean to say that you only have one system? If there wasn't another Wii game for the next 4 months, I'd still be able to play some of the olde GC games, and barring that there are plenty of games which I have picked up for the PS2 (I'm looking forward to Rogue Galaxy (Feb. 1), Tomb Raider Anniversary and God of War II; I've just picked up Grandia III, King of Hearts I, II, Dark Cloud I, II). (On the GC side I have picked up Mystic Heroes, King of Persia: Darkness Within, Sphinx and the Cursed Mummy. Soon I'll be getting Resident Evil, Resident Evil 4, Eternal Darkness, Rogue Squadron, Zelda: Wind Waker.)
I say either buy a PS2 and get as many great games as possible, or, if your budget is set, sell the Wii and get the 360. Me, I'd rather get a lot of older games for $6 - $20 than pay $60 for a 360 or PS3 game. Yes, I paid the $50 for Z:TP and I'm even thinking of getting Z:TP GC version.
If it's all about the games, then the PS2 and XBox probably occupy more shelf space at your local Block Buster's or Hollywood Video.