We stayed at Magnolia Terrace the last two times we went to POR, and we'd like to stay there again. I did, in fact, request Magnolia Terrace when I made the room reservation through Disney.
Maybe a faxed (re)-request is not necessary?
I did read somewhere that faxed requests are more effective, and that it's smart to send one even if the request has been made with the reservation.
We're going in late January, so I'm sure that with the light crowds it won't be a problem getting into Magnolia Terrace. I just like to cover my bases.