Have fun planning your May trip now!
I am also hoping to go to Disney World in May. Have found lots of useful info on DisBoards (Thanks!!).
The only reason I have not yet booked is that I want to have a look at DDs school schedule first. She will be going to a private school and their days off (teacher in-service,etc.) are not the same each year. I would like, if possible, to schedule vacation around some of her scheduled days off, so she will not have to miss a whole week of classes. Feel a bit guilty about pulling her out of school at all, but this will be her first vacation in 9 years, and I want it to be at a great time of year, weather-wise, crowds-wise, etc. She will be in the eighth grade...
Have done lots of pre-planning, though. Even spoke with a TA to find out current airfares, '05 rack-rates for on-site rooms (hope to get an AP and be able to use a discount code for room-only, moderate resort!), all this preparation so I will pretty much be able to just book it in Sept., when the time comes!