it's a global windows setting affecting your desktop and all programs.


On Windows Vista/7: Rightclick desktop and select personalize. In the menu to the left. Select "Adjust font size (DPI)"
The default is 96DPI which is what screens have been (more or less) been using since the time of CRT's.

You can set it to any custom size you want via the Custom DPI button. The default windows UI doesn't allow for anything less than 100%, but there's utilities that let you scale down.