Reinstalling Adobe Acrobat 9.5.5?

I have recently removed Adobe Acrobat 9.5.5. from my second computer.  I did not deactivate it.

I have the following questions: -

1. How do I re-install Adobe Acrobat 9.5.5?  I still have the Serial Number from my other computer, if this helps.
2. Once installed, I will be looking at upgrading to Acrobat X1.  How do I do this?

Look forward to some help here.

Thank you