hi,
Your welcome to SCF and hope u enjoy learning how to use SU7. As for you request, I'm a little confused as whatvyour attempting.
You can EXPORT your model in many different image formats that Word will accept.
You're adding pictures from Xcel to a Word document containing an exported image from SU7 after editing them in GIMP. Is that correct?
Have you looked on the 3d warehouse for anything that might help so all your work is on one platform.
Try posting an image of what you're doing so members can advise on the best steps to take.
Sorry I wasn't more helpful but you'll find lots of good advice here. You're current method of workflow seems a little muddled without more info or image to better explain.