You can rent them out for now, assuming there is availability and you are within the booking windows.
Feb 2003 points are good for stays between 2/1/2003 and 1/31/2004.
Feb 2004 points are good for stays between 2/1/2004 and 1/31/2005. However, you can borrow 2004 points for stays between 2/1/2003 and 1/31/2004.
Keep in mind that there is some addtional risk if you borrow points to make a reservation for someone else. Once borrowed, the 2004 points cannot be returned to their original use year (2004). Be sure you have some safeguards built into your rental agreement if the renter has to cancel/back out. If you borow the 2004 points for use in the 2003 use year, and they are not actually used before 1/31/2004, you will lose them.
Good luck!