Hi OfficeNinja,

The native file formats for Office 2007 & later already uses zip compression. The docx, xlsx, etc extensions are there so that Windows knows which applications to open them with. Applying further compression won't achieve much - and could actually increase the file size due to the space required for storing the compressor's file tokens.

If you change the docx, xlsx, etc extensions to zip, you can then use other software to examine these files' internal structure.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]