Eric White -> Transforming Open XML Documents to Flat OPC Format

If you're doing anything with Office Open XML, then you need to read this article by Eric White.  In it, Eric describes a very nice approach that lets you gain full leverage out of XSLT when dealing with Office Open XML documents.  Basically, he starts by converting a .DOCX file (or .PPTX or .XSLX) to an intermediate format (Flat OPC) that retains the same structure as a standard package file, but in a single XML document.  Then you simply apply your favorite XSLT transform and convert it back into a package.  Voila! Instant transformation without all that messy system.io.packaging code.  Included with the article are the two conversion routines you need and lots of sample code to play with.  Great stuff!