A "site" you might want to build on your PC is a "catch-all" site for monitoring module and theme status with the Update Status module.

This module will check with the Drupal site and let you know if newer releases of your modules are available.

Many people eventually find that they need (want) to patch, tweak, or otherwise modify modules or themes. If you create a "catch-all" site, you can place unmodified code here so that you always have a "clean" copy to fall back on. You can then copy it to the correct site before changing it. Now, not only do you have the fall-back plan, but you get the added advantage of knowing if it needs to be updated.