Kelly, all you can do is ask. It is at their discretion whether or not to do it, but I would book it now if you want the secret porthole (the Early Booking Savings will be better now too).
kendall, the 2005 rates are not out yet and everyone gets them at the same time.
There are sometimes better Early Booking Savings offers when booking onboard, in addition to the onboard credit, it just depends what promotion they are offering. But a word of warning, if you are booking onboard, do it early on in the cruise or you could risk losing out.
Hope that helps,
Cathy