updating a frame from within php...

hi... this probably doens't belong here.. but i'll try! i have a two frame window. when the user logs into the 'main' window, i want to be able to 'update' the 'main' window and then hte 'nav' window. some underlying vars are getting set, and i need to be be able to refresh elements/links in the 'nav' window with the new values... searching through google, hasn't really shed any insight/light on the best approach for this.. any ideas/pointers/comments/thoughts... thanks -bruce