Just a note:
I called MS to to bank points in 2003, and was told that since I had already banked points once that year, I could not bank again. Knowing the rules I tried to convince them I was right. They would not listen, so I ended the call, called back, got someone else, and banked my points. The second person said I must have mis-understood the first person.
Moral to the story, know your rules.