I'm guessing you mean resize as in keep the same size but compress? It isn't 100% clear from the above but given the title of compression and keeping the formatting I'm guessing the size is actually staying the same i.e. the images aren't being resized but the file size is being reduced?
I would say this could be done via some nifty VBA. Are all the source images in the word document of a particular format e.g. BMP or JPEG or are they a mixture?
I'd be happy to have a go at a solution. Are the documents confidential or could one be emailed to me to take a look at?