I had the same problem with a recent hub using an Excel graph.
Use the "snippet" tool in windows 7 to take a shot of the area. (click the "start" button and type "snippet" in, choosing the correct program). Alternatively, use the "print screen" to take a screen shot.
Paste it into a photo editor, crop as necessary, and save it. You can now upload the "photo" to HP and use the photo capsule to show it in a hub.
Simone and wilderness both have great suggestions for capturing screenshots. You might also want to check out the free capture and annotation program, Skitch. It is avalable for iOS, Android, OS X, and Windows. You can find it here: http://evernote.com/skitch/
You can then save the image and upload it to your HubPages account.