Here is a simple tip to back up your entire WordPress blog, users, posts, and Images.
Firstly Backup the Text content
Go to your blogs admin section, Manage > Export to download it in XML format, further this can be used to import to your latest wordpress version.
Then Backup the images
Download and install the Firefox extension DownThemAll, then login to your your WordPress blog’s admin section
Manage > Media Library page & set DownThemAll to download all your image links on the page, you are done with it. Isnt that simple.