Windows Vista includes Internet Explorer 7, and on a new install it defaults to Microsoft's Live Search, which is just terrible. Here's the easy steps to make Google the default search engine instead.

First, open up Internet Explorer, and then click the little search dropdown:

You should see a page with Google Web Search on it:

Click Google as fast as you can!

Make sure you check the default search provider box.

This will also work in IE7 on XP as well.