by Ken Task.
Mybe the resident Windows expert (Osman) will grace us with his involvement here.
So, just to make sure any others that read this thread also understand ... you can upload PDF's, Word Docs, whatever into a course using the normal add a resource, etc. It's just backups you cannot restore by any method - .mbz files.
About version 2.6 Moodle changed from zip archiving to what it called experimental at the time (Gzipped and Tarred) format. The .mbz file could still be a zip or it could be the new now default gunzipped/tarred type file.
So on your PC, make a backup .mbz file and download it to your Windows 7 desktop in a test directory/folder. Then change the extension (the .mbz) to .zip. See if you can un-zip it. If you can't, then the file is a gunzipped file. Change extension back to .mbz and get software installed that will un-compress a gunzipped file.
In order for Moodle to work properly, there must be PHP extensions loaded on whatever you are using as a server. The two dealing with zips ... php-zip and php-zlib.
All Moodles (for as long as I can remember) have in site admin menu, a server menu item and under that PHPInfo.
In the display of php info, one should see a zip.ini in additional .ini files parsed, a Bz2 section, zip, and zlib.
Will make this comment, didn't think Windows 7 was meant for server anything.
https://www.google.com/search?q=Windows+7+as+server&ie=utf-8&oe=utf-8
Some folks do it but think none stick with that XAMPP package ... and eventually install things like true IIS etc. as well as move to a true server OS ... maybe even Linux.
So ... CALLING ANY WINDOWS PERSON ... you're up! ;)
'spirit of sharing', Ken