WordPress Backup and more …
BackWPUp is one of the best, free, back-up plugins allowing you to backup all of your WordPress install, including the database, or just selected files to a specific folder, ftp server, Amazon S3, Google storage, RackSpaceCloud, DropBox amongst many as well as simply email the lot.
Backups can be formated as zip, tar, tar.gz, tar.bz2 etc and you can also optimize, check and repair the database.
Depending on the project I’ve personally used BackWPUp many times over the years and have found it to be stable.
Set it up, done. Leave the cron job to run itself at specified times.