StarOptions don't carry over, so you need to do something with them before the use year is over. If you don't want to travel this year, you could deposit with an external exchange company, which depending on the company, could give you a few extra years to use your week.
From the User Guide on mystarcentral:
"Unused StarOptions expire on the last day of each use year and do not carry forward.
You can borrow StarOptions from the next use year, to customize this year's vacation. To do so, you need to:
Pre-pay all fees (maintenance, taxes, Starwood Vacation Network membership fees, etc.) for the year you are borrowing from at the time of making the reservation
Borrow within 90 days of the desired check-in date
Borrow only the number of StarOptions needed to complete your transaction"
I don't see anything in the User Guide specific to EOY and borrowing. You may want to verify that it works the same way by submiting the question on mystarcentral or perhaps someone else here knows the answer. The way I read that is you may borrow options from 2008 to use in 2007. But this is likely not the most effective way to use your ownership, since most of the good reservations are gone by 90 days prior to checkin. Most of the experienced SVN folks here on TUG attempt to make their reservations first thing in the morning on the first day that their desired dated opens up (12 or 8 months in advance, depending). I would think that pickings would be pretty slim at 90 days out. I guess it depends where and when you want to go.
Or, you have until March 31st to convert to StarPoints, if you want to go that route. But you can only do that every other use year. For instance, if you convert in 2006, you won't be able to convert in 2008. The next time you could do it would be 2010.