where can I download free adobe old versions?

http://www.download.com

Do you mean adobe acrobat reader?
You can download from the official site of adobe and you can try some of the website would post the old versions.
If you are talking about other professional software, such as InDesign, Photoshop...
I am not sure if they are piracy or illegal.

There probably isn't a legal way to do that... Adobe holds to it's copyrights pretty strongly...

However, if you need to make PDF files from documents, you can use the free, open-source program OpenOffice.

If Image Editing is what you're looking for, look no further than the GIMP! It rocks. It is also free open-source.

Open source software is the best... it's programmed by community members during their free time, and in the case of a few projects, has produced some amazingly good pieces of software. If only someone would write up a free PDF editor, life would be perfect.