Windows Vista Update

new pc with vista will not play games????

We bought a new PC for Christmas, with the VISTA on it.
We are trying to play games, but they will not load.
Are there any updates or patches available?
The game is "Cars" for the PC??
There are other games that will not play, the "Nancy Drew" games will not load also??
Any more, once you buy a game you can't take it back and get something else??
I hope to hear from some one soon, the kids are getting a little upset???
Thanks!
Angela