if you're talking christmas time, value season is november 27th through december 19th this year for example. so if you got married during this festive time you would have all the decor (all the parks & resorts are decorated) & special christmas events (like mk's mickeys very merry christmas party & epcot's christmas processional) with value season prices starting at $77 a night the value resorts & $199 for deluxes which is a steal.
however if you wanted it the week of christmas or new years a) the price would be way more during this peak/holiday season rate and b) i believe the price does increase for the actual holiday wedding 12/24, 12/25, 12/31, 1/1. *another wdw bride could probably verify that more*
if you want a holiday wedding at wdw i would definetly suggest during the value season november 27-december 19 (similiar dates probs for 2006) with all the trimmings. we have visited during this time & it is just awesome. best of luck!