Since the Microsoft recorder that comes on PCs only allows you to record about 45 seconds of audio, you'll probably have to use some other software. This one looked pretty good:
http://audacity.sourceforge.net/
It's free and seems to work pretty well. You won't have professional recordings reading your books, but it will be good enough for most things. For example, if you were recording so your children could listen to you reading them stories, etc.
You really didn't clarify what you wanted to do, so hopefully this will help you.