With the initial Vista UAC people were trained to just click yes to everything or they would turn off the function entirely. With Windows 7 it is far less frustrating but the User part of the UAC is what is broken, there is no substitution for actually educating users. That is something that is far out of MS's reach IMHO.

The IYA project 365 Days of Astronomy Podcast has been excellent so far as well - for when you are stuck commuting in a light-polluted city this year. http://365daysofastronomy.org/

When we were snowed in last week my daughter and I played some Wii tennis. She's 3.5 years old, bowling was a bit much for her and she lacked the eye-hand coordination for the baseball game. She also likes to hop around on Dance Dance Revolution mats, but is pretty far from being able to line up steps with the screen.
I know I was a Pac-man player around age 5-6, but with the Wii being so engaging I can see kids taking off using it sooner. Plus in areas with terrible weather it is a nice way to keep kids moving when outdoor play is not available.