I am working on allowing users to modify their screen font size in wondows 7. I tried editing the group policy outlined above in this thread and it had no affect. I then found another Group Policy that deals with this same issue. It is here;
User Configuration/Policies/Administrative Templates/Control Panel/Personalization/Prohibit selection of visual font size
It needs to be set to Disabled.
Once I made both the change listed above and this change, the options to modify the screen fonts were no longer greyed out.