We are just back too from 10 days in WDW. The parks were crowded at times, but NOTHING like Christmas 2000! We took advantage of the sudden cold weather Monday night. MK practically cleared out completely by 9 PM and we walked on all the rides until 11PM closing. We thought it was great, but we also were prepared for the cold with sweathshirts and jeans so it was nice for us. I saw a LOT of people buying beach towels to cover up in (must be cheaper than sweatshirts?)
All in all, we had a great time, and were not surprised by the crowd sizes, nor did we feel they were overwhelming. It was a good time to go, but you need to be prepared for all sorts of weather!