yah, there's nothing to do about this if you are using internet explorer...short of changing your screen resolution (Which you should REALLY do anyways...).
However, if you have Firefox, one way to get around this, is to right click on the thumbnailed image, and do "View Image". This will load the image in the window that the thread was in. It should automatically resize the image for you. Then, once your done looking at it, you can just hit the back button to get back to the thread.