the latest verison of Camtasia says to open the old projects and save as. I can't do that for two reasons- I don't have version 8 (only 7.1). And my version of 7.1 will no longer open. Is there any other way to recover existing projects?
Install that as the Trial Version, open each project and do a Save As > (New Name) within the same project folder so all your media is still linked. This will upgrade those project and will leave your originals untouched.
Please keep in mind, that Camtasia 9 is VERY different from Camtasia 7. So, your projects will most likely need some editing/rework on them to get them into a state where they are usable.