You can vary the font size in many applications including the Adobe Help Center and Internet Explorer in the following way.
Download and install a Power Toy from the Microsoft site called "Tweak UI". Start the Adobe Help Center, click in the right help pane then while holding down the Ctrl key turn the mouse wheel to change the font size. It may work without the Power Toy but in any case the Tweak UI Power Toy gives you access to change numerous hidden settings in Microsoft Windows XP (SP1 and later).
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