If you have a blog, you should be backing up your blog. If you don't have access to the server directly, the easiest way to back up your blog is to use BlogBackupr. It allows you to back up wordpress and blogger blogs. It backs up your blog entries, comments, images, templates and everything else that makes your blog unique. It also allows you to restore your blog automatically.

There is no software to install on the machine hosting your blog. It gets access to all the files that it backs up over the internet.