I won a gaming console which should I get??

[BengaBenga]

I'd go Wii. PS3 has nothing you can't already play on your 360.

With Wii you can play Mario Galaxy, Metroid 3, Zelda TP, Zack & Wiki, RE4:Wii, Paper Mario, RE:UC

and will play in the near future:

Smash Bros Brawl, Mario Kart, Fragile, FFCC, Tales of Symphonia2, Fatal Frame 4, Spore,

(all the above are (console) exclusive for Wii)

With Wii60 you'll (probably) miss out on:
Metal Gear Solid 4, Gran Turismo 5, FF main series, Uncharted, Ratchet & Clank

But very good substitutes:
Splinter Cell 5 (360), Forza 2(360), Lost Odyssee (360), Metroid (Wii), Super Mario Galaxy (Wii)

Good luck with your choice.