I have a 360 & Wii. My 360 is modded to play copied games and I don't even play it. I buy original games for the Wii - The wii totally took over in our house. My 4 year old daughter and wifes 80 year old grandmother both love playing Wii Tennis. We play on a 42" HD TV - ok, it might not output HD etc. But the picture is pretty damn good in my opinion and the game play is amazing.

You get into the games way more with the different forms of interaction the Wiimote gives you over a normal 360 type game. I definitely recommend the Wii if you can get hold of one, they are still hard to come by in these parts.