Gmail has quickly become the only email service I use other than my company account, and I also use Google Apps for the websites I own. So all in all I am in good hands, but there is also a risk to lose everything if something goes wrong.
Though I setup most of my Gmail accounts in Windows Live Email which in itself creates a local backup, not all attachments are downloaded to my local PC. In such situations the Gmail Backup is a excellent software, which will allow you to backup your entire Gmail account offline.
Related: Backup Files To Your Gmail Account
Gmail Backup will allow you to download all the emails and attachments to your local machine, and it is not just a one time process since it provides you with incremental backups, where only the emails that have not yet been backed up to your computer will be downloaded.
In addition to that you can also specify the dates from when you want to backup your emails. Gmail Backup requires you to enable IMAP access in your Gmail account. The software works on Windows and Linux based machines.
So take advantage of this handy free software and backup your Gmail account just to stay safe from any disasters.