I have a perfect printed listing of an address group, When I print address labels I get a variety of fonts and sizes. The 'Font Set' facility in print window appears to have no effect
Be sure you've checked for any troublesome fonts (all languages) with Apple's Font Book (look in the Applications folder). Find and remove all duplicates also.
Start there to be sure all fonts that are in play come out with a clean bill of health.
Don't hesisate to perform wholesale deletion of old and/or little used fonts - be skeptical of anything that has come from Office 2008, including those related to an Equation Editor installation.
And by all means be sure any 3rd party apps AND plug-ins are Snow Leopard compatible.