If you invest any time in your WP blog you should back it up. It doesn’t matter if your host already does it two copies is better than one, especially if yours is stored on your PC or inbox that you have instant access to.
I did this, I’m not very technical and it took literally 60 seconds:
-Download this: http://wordpress.org/extend/plugins/wp-db-backup/installation/
-Copy the wp-db-backup.php file to /wp-content/plugins/
-Activate the plugin at your blog’s Admin -> Plugins screen
-Take an immediate backup now by hitting ‘Backup’
-Set it to email you your backup as often as you want it hourly/daily/monthly..
*The plugin will attempt to create a directory /wp-content/backup-*/ inside your WordPress directory.
You may need to make /wp-content writable (at least temporarily) for it to create this directory. Most of us I expect use an ftp client like filezilla, right click on the wp-content folder and click file permissions to change them.
Simple. Go do it now!