Word to GIMP pasted image too small
Solution 1:
Well, the format Office stores the images copied to clipboard is WMF (I think it is the reason of your problem). If you open Windows clipboard manager (start > execute > clipbrd), you can see that the default format is a metafile (View menu, the first option bellow "default format").
I think you can solve that problem easily using another clipboard manager. But you can try that to solve by another way:
option 1: save your document as html and open the image you want on Gimp.
option 2: open the document, see the page with the image, do "print screen" and then paste to Gimp and cut what do you want (you can zoom the page to copy with better quality).
option 3: open the document on OpenOffice, right click on a figure and select "save image" (if you cannot open DOCX, save in your Word as DOC).