Two houses I have looked at (to buy) have had cracks under 2 or more
windows, and also above the windows.

What does this indicate and is it possible to fix? and how much could
it cost to fix?

One house I have pictured here, I have drawn the cracks on the
picture.
http://img367.imageshack.us/img367/5472/wall01awn5.jpg

Hopefully the image wil work - imageshack has not been very reliable
of late.