I had the same issue when it came to learning Blender the use of so many different version but now I keep and run several different version on my Machine just so I can do some tutorials as I learn. I do not know if you knew you can run Blender right from a zip version? I keep on my machine Blender 2.49, 2.50 2.63, 2.68 and the current version these to me were sort of major releases where major changes happened and covers most of all the tutorials out there that you can find. Just a thought if you wish to do older tutorials just download a older zip version and run blender right from the zip it does not have to be installed.

Good Luck

Thanks for that Lobo3433

Great idea, and thanks for that tip about the zip files.  I hadn't thought about running separate installs.!