Backup

From TreoCentral

As with any software program or device, it is critical to maintain a good backup. That way, if any data is ever lost or accidentally deleted, you can restore a saved version.

When you successfully complete a HotSync, the Desktop HotSync application will save a copy of the data in case it ever needs to be restored. However, there are better, more convenient 3rd-party solutions available as well (such as Resco Backup) which allows you to save your Treo data to your SD card.