wp-blog-header.php.hacked

Hi folks,

I was in the process of backing up the public files on a website (www.miriammedical.co.uk/dynamic) in order to delete them and make public the new version of the site, which is currently hosted on a subdirectory (www.miriammedical.co.uk/miriam2012)

I found a file called wp-blog-header.php.hacked with a filetype of “hacked-file”!!

Does this mean my header was hacked, or does this file exist to STOP the site being hacked?

And if I delete this directory, and simply move my new site in its place, will I be safe, or do I need to do anything else?

Thanks!