Check this that is on the first page of this thread for the backup utility:
http://www.rockettheme.com/forum/index.php?f=92&t=46753&rb_v=viewtopic#p243903
Backup rule of thumb: Run backups often enough so that if you need to use a backup to reload your site, you have enough information recovered to keep you happy. If your site is updates often like a very active forum, maybe update that database daily. If you load your template and content into the joomla site once and you're done, you only need that one backup.
I've been making posts in this thread that include links to Joomla's directions for updates of each version. Here's the post just above here for 1.5.9:
http://www.rockettheme.com/forum/index.php?f=92&t=46753&rb_v=viewtopic&start=30#p265005
Here's Joomla's directions for updates:
http://docs.joomla.org/Upgrading_1.5_from_an_existing_1.5x_version
Really what you're looking to do is find the correct update package, unzip it, and FTP it over your site files overwriting the old ones with the new ones.
prim wrote:
Just go to this site and check the patch versions
http://joomlacode.org/gf/project/joomla/frs/