In Birnbaum's Guidebook, the following dates are listed. They will vary slightly depending on the date President's week is.
Value Season for 2001:
Value and Moderate Resorts, WL, AKL, and FW Cabins: Jan 1- Feb 14, Aug 26-Sept 26 and Nov 4-Dec 20
Swan & Dolphin: Jan 1-15 and May 1-Dec 22
All other WDW properties: Jan 1- Feb 14, July4-Sept 26, and Nov 4-Dec 20
If you look at a calendar and see the days of the week that these days fall on, you can make the adjustment and get an idea of when value season will be for 2003. The July 4-Sept time period is the same each year at the Deluxe resorts.