In Apache 2 I added the following to stop Internet Explorer trying to open these formats as compressed archives (which they actually are) and to open them using the MS Office appliations:
AddType application/vnd.ms-word.document.macroEnabled.12 .docm
AddType application/vnd.openxmlformats-offic edocument. wordproces singml.doc ument docx
AddType application/vnd.openxmlformats-offic edocument. wordproces singml.tem plate dotx
AddType application/vnd.ms-powerpoint.templa te.macroEn abled.12 potm
AddType application/vnd.openxmlformats-offic edocument. presentati onml.templ ate potx
AddType application/vnd.ms-powerpoint.addin. macroEnabl ed.12 ppam
AddType application/vnd.ms-powerpoint.slides how.macroE nabled.12 ppsm
AddType application/vnd.openxmlformats-offic edocument. presentati onml.slide show ppsx
AddType application/vnd.ms-powerpoint.presen tation.mac roEnabled. 12 pptm
AddType application/vnd.openxmlformats-offic edocument. presentati onml.prese ntation pptx
AddType application/vnd.ms-excel.addin.macro Enabled.12 xlam
AddType application/vnd.ms-excel.sheet.binar y.macroEna bled.12 xlsb
AddType application/vnd.ms-excel.sheet.macro Enabled.12 xlsm
AddType application/vnd.openxmlformats-offic edocument. spreadshee tml.sheet xlsx
AddType application/vnd.ms-excel.template.ma croEnabled .12 xltm
AddType application/vnd.openxmlformats-offic edocument. spreadshee tml.templa te xltx
