As a Dreamweaver user, you have the following options to back up your site definitions. You can:
Use the MM-Exporter extension (Windows user).
Note: This extension currently does not recognize Dreamweaver 8. An updated version will be available in early 2006.
Tip: Always print out and store everything that contains the remote server access data, even if you are a paperless office fan!
Your backup strategy also depends upon the number of site definitions you want to back up. For a single site definition or a small number of site definitions, the best way is to use the export and import functions of the Dreamweaver site manager. If you have to back up many site definitions at the same time, you might be better off working with the Dreamweaver Sites registry key (Windows users) or back up the Site Prefs file (Mac user).
The only way to transfer site definitions between Windows and Macintosh platforms is to use the export and import feature.
Note: Don't forget to edit your site definitions after importing the site definitions on the new operating system. You'll have to point the site folder to the correct local folder where all the site's files are stored!