I searched all over the Web and i was disappointed about changing font in Outlook (Office 2007) but now i finally found this Nice helpful Topic.
it is exactly that i was looking for.
i think changing the pane by customizing view that dear
hvaldez and
FightingScallion mentioned.
about that bad news can not changing Navigation Bar default font i am searching too and i hope we do it at least by a trick in Regedit.
anyway a Big Thanks from Iran.