There was a recent thread which had a lively discussion regarding this topic.
http://www.disboards.com/showthread.php?t=1605808
In looking at the numbers, it is a really bad financial move to use DVC points for
DCL (or for anything other than DVC resorts).
You are far better off transferring or renting your points rather than using it for a
Disney cruise.
There are other disadvantages, the main one being that if you cancel, you don't get the points back as DVC points, they get changed into reservation points. There are other restrictions as well as a $95 non-refundable "exchange fee" on top of the points.
The best thing to do is pay cash for the deposit, then, if possible, convert that reservation later into point usage, if you are able to do so.
Cash, you can cancel as late as 91 days prior to the cruise, and get a full refund.
Look carefully before you make that decision regarding using DVC points for DCL... it is a really.... well, ill-advised, is the kindest term for that action.