I've seen this discussed on TUG (www.tug2.net) but I don't have a link to the info. It might be on the vacationclub site for Marriott owners.

However it isn't a guarantee for 5 nights. It's just a 5 night travel package. I think the cost is the points for the 5 nights and the airline miles added on to that amount. Just like a 7 night package, only for only 5 nights so it costs less.