Great idea, but it occurred to me that this could possibly be done with a little less work.
I prefer to only use one compression utility and as I sometimes need to transfer large backups back to the office over an RDP connection I need to compress them first and as WinZip won’t handle files large than 4GB it isn’t of use to me. Instead I use 7-Zip which handles zip, rar and iso files as well as it’s own 7z archives which get a better compression ratio than zip.
In Windows Explorer, I right clicked on the Word .docx file and selected 7-Zip on the context menu then selected Open Archive;
As David described, I navigated down through the archive structure into the Word/Media folder and there were the images in the .docx file.
Extracting images in this way hadn’t occurred to me but, as David pointed out, .docx and the other document types are all, basically, disguised archives so this should be possible for all Microsoft Office 2007 or 2010 document types.