Here you will find a list of resources to get you started and point you in the right direction in your quest to discover the truth about the Pythagorean Theorem. This list should not be the only resources you use.
Wikipedia-A good basic place to get general ideas of what is going on http://en.wikipedia.org/wiki/Pythagorean_theorem
An animated proof of the theorem
http://www.usna.edu/MathDept/mdm/pyth.html
Interactive site showing how to find distances on the coordinate plane http://math.about.com/gi/dynamic/offsite.htm?site=http://cs.selu.edu/~rbyrd/tutorial/tutorial1.1.html
An interactive site with Practice Problems that have 3 levels of difficulty http://www.shodor.org/interactivate/activities/PythagoreanExplorer/
The Pythagorean Calculator, just input your numbers, and it does all the work, great to check your work http://www.1728.com/pythgorn.htm
An animated proof of the theorem
http://www.usna.edu/MathDept/mdm/pyth.html
Interactive site showing how to find distances on the coordinate plane http://math.about.com/gi/dynamic/offsite.htm?site=http://cs.selu.edu/~rbyrd/tutorial/tutorial1.1.html
An interactive site with Practice Problems that have 3 levels of difficulty http://www.shodor.org/interactivate/activities/PythagoreanExplorer/
The Pythagorean Calculator, just input your numbers, and it does all the work, great to check your work http://www.1728.com/pythgorn.htm