Just to clarify a little bit -
You cannot book/make a reservation AND travel/stay at a non-
DVC option during the last 60 days of your use year.
With a February use year, you can certainly stay at a non-DVC option during December and January. You just have to actually make the reservation for the stay more than 60 days ahead of the end of your use year. For example, let's say you wanted to stay at the Poly on points 12/7/2003 - 12/15/2003. You would have to call MS before 12/2/2003 to make the reservation. If there is availability at the Poly, you would get your reservation.
The reason for the rule is to give MS time to rent out for cash the equivalent number of room nights in a DVC resort to "pay" for your stay at the Poly. Since availability at DVC resorts is often very limited 60 days or less ahead of arrival, MS would have a very tough time doing that without this rule and the points would expire on them. If they have trouble recouping the $$ to pay for a stay at a non-DVC option, the point cost for those options will go up even higher.
As Bill posted, you can make a reservation for any of the DVC resorts at any time (subject to availability and all of the cancellation guidelines, of course).
HTH.