If you end up going with the Wii, make sure your wii-motes have good tethers and if you have children
strictly enforce usage. I don't know if there are any warranties that cover a screen getting destroyed by a wii-mote impact; but I know that most manufacturers call that non-warrantable damage.
Do remember that if you don't have a blu-ray player, the PS3 will get you that. Personally, I don't have a PS3, but I don't have a big HD television, so I won't be upgrading anytime soon.