If you are looking for a way to back up your WordPress site, this is a great option that is simple to set up and can backup your site for you automatically. BackUpWordPress will back up your entire site including your database and all your theme files once every day, week or month. This is a free plug in that can be found in the WordPress Plugin Directory.
I have been using this plugin since the beginning of the year. I have found this to work very well, and use this on every site that I build now.
You have the option to do a manual or automatic scheduled back up. You can do daily, weekly, bi-weekly or monthly backups just by setting the frequency. You even have the option to have that zipped backup file sent by email to you. You can also set the number of backups to be kept on the server.