Help please! Install/migrate/downgrade

Hello ryan211 and Welcome to Ubuntu & Linux
Mint is a good Distro but it is based on ubuntu 14.04 and would not be much lighter. What desktop are you using now if it's unity you would benefit from changing to a light desktop enviroment, such as mate, xfce. or lxde you may want to try out lubuntu or xubuntu or ubuntu-mate - They will run better on your equipment.
if you need something lighter than those i would suggest Anti-x.

In any event give us a little more info on your system and we would be able to give better advice.
as for the saving your info -- that again will be hard to tell you what to do unless we know what's already installed and if you have a seperate /home partition or not.
it can be done. But my advise is to save any important documents and files to an exteal media of some sort and do a fresh install.

Good luck