Scott Hanselman points to a macro that should be useful for code presenters that allows chaning the font size in VS.NET to the appropriate presentation size. Cool.
Another way to do this is by calling your VS.Net devenv.exe with a command line argument specifying the font size in which to display everything:
C:\[My Devenv path]\devenv.exe" /fs 40
this will load vs.net and all fonts in dialogs and source will be set to size 40. very scary!