If you upload an Office 2007 document to moodle and attempt to download it. Example being Word 2007 .DOCX file, it sends the file as .DOC, stripping the .DOCX file type. Here are the actual Office 2007 MIME Types that I had to specify in filelib.php and a copy of the filelib.php that works on multiple sites. Reference http://moodle.org/mod/forum/discuss.php?d=102716.

application/onenote onetoc onetoc2 onetmp onepkg
application/vnd.ms-excel.addin.macroEnabled.12 xlam
application/vnd.ms-excel.sheet.binary.macroEnabled.12 xlsb
application/vnd.ms-excel.sheet.macroEnabled.12 xlsm
application/vnd.ms-excel.template.macroEnabled.12 xltm
application/vnd.ms-powerpoint.addin.macroEnabled.12 ppam
application/vnd.ms-powerpoint.presentation.macroEnabled.12 pptm
application/vnd.ms-powerpoint.slide.macroEnabled.12 sldm
application/vnd.ms-powerpoint.slideshow.macroEnabled.12 ppsm
application/vnd.ms-powerpoint.template.macroEnabled.12 potm
application/vnd.ms-word.document.macroEnabled.12 docm
application/vnd.ms-word.template.macroEnabled.12 dotm
application/vnd.openxmlformats-officedocument.presentationml.presentation pptx
application/vnd.openxmlformats-officedocument.presentationml.slide sldx
application/vnd.openxmlformats-officedocument.presentationml.slideshow ppsx
application/vnd.openxmlformats-officedocument.presentationml.template potx
application/vnd.openxmlformats-officedocument.spreadsheetml.sheet xlsx
application/vnd.openxmlformats-officedocument.spreadsheetml.template xltx
application/vnd.openxmlformats-officedocument.wordprocessingml.document docx
application/vnd.openxmlformats-officedocument.wordprocessingml.template dotx