Check the FAQ "stickies" over on the Rent/Trade Board for more info.
Renting requires a considerable amount of research, and the ability to stick to reservation dates made long in advance. The most important factors, IMHO, are both parties fully understanding the transaction, and both parties having a good level of comfort with each other. Because of the work involved and the potential difficulties with cancellations, it is not for everyone.
However, if you are comfortable with the rental process, you can save a considerable amount of money on a trip to WDW.