Have you ever tried to learn about X-ray crystallography from a book? If you haven't, I can tell you that it is not so easy.
Spending 5 hours with these 2 sites is the equivalent of reading 10 crystallography books.
Lots of great links too.
http://www.ruppweb.org/Xray/101index.html
http://www-structmed.cimr.cam.ac.uk/course.html