If you try to open a project for a version you do not have, then you should see an option to convert the project to a version you do have. You don't need to perform an import. It will convert it for you.
But, if you convert a project from version 20 to say, version 32, then it will no longer be compatible with your version 20 controller. It does save a copy of the old file though so if you forgot to make a copy you do have a way to recover.
So ideally you want to add version 20 software to your PC. It will install and run fine along with your existing version(s). They are meant to be installed alongside each other. As ASF mentioned earlier, the software will inspect the version whenever you open a file, and it will open the proper version of RSLogix/Studio 5000. My virtual machine has version 13 - 33 installed together.
OG