I have gone under the Accessibility Tab and increased the Font Scale for the IPTC Caption Field to 140%.  Works great when I have my dummy caption in it.  When I go to enter the real text it reverts back to the default size.  Sort of defeats the purpose of the increased size.   To be clear in my caption field I will enter:
17 August 2012:  xx in action against XX at Nationals Park in Washington, D.C. where the Washington Nationals defeated the New York Mets, 6-4.
When I replace the first xx with a code replacement value like \w34\, then the whole text field reverts back to the default size.  
Running Windows 7 64-bit on an Intel i7 quad processor with 16GB of Memory.