I have Windows 7. and Audacity 1.3 Beta
If I upgrade to the latest version will I lose all my files from the old version?
Personally I don’t encourage keeping Audacity projects as “projects”, because (a) Audacity projects are huge, (b) it is essential that all of the audio data remains available for the project, (c) In old versions of Audacity it is not easy to see if the project is self contained or has “dependencies”. If you intend to do further work on the project (more editing, processing, recording), then yes you should keep the project, but it is essential that the audio data for the project remains available to the project. When a project is completed, much better to keep a high quality WAV or FLAC file as the archive backup.
If the above is not totally clear to you, please see here for more information about Audacity projects: http://manual.audacityteam.org/man/audacity_projects.html
Assuming that you mean “Audacity Projects”, I’d suggest that you first check with your current version of Audacity that they are working correctly. If the projects are OK, then Audacity 2.1.2 will be able to open them.