Setting a default font using the Windows 7 Outlook programme, can you tell me how?

I don’t like the default font that comes with the Windows 7 Outlook programme, there are lots of other nice fonts available to use but I want to set one of them as the default font, I did this when running Windows XP Outlook Express but cannot find a way to do it on my new computer? If you can explain to me how to carry out this operation I would be most happy.