I have been flying to WDW with my laptop for several years now. There are several special preparations you can make to get through security easier:
1) Carry the laptop on board with you - don't dfare put it in checked bags!
2) Empty the whole laptop bag out and re-pack it when you pack your regular luggage, to make sure that there are no prohibited items in the bag.
3) When you pack the laptop bag, practice to make sure you can get the computer itself out of the bag while it is hanging from your shoulder, without spilling the rest of the contents out. You will have to remove the computer from the bag and sent it through the x-ray machine in its own plastic bin.
4) Since you are carrying the laptop bag anyway, put all of your travel documents - air ressie, boarding pass, rental car/towncar/DME info, and hotel confirmation - in one of the easily accessible outside pockets. Convenience!
5) Since you have to empty your pockets before going through the metal detector, empty them before you even get into the line and put everything into one of the laptop bags compartments (don't forget your cell phone, watch, jewelry, etc). It is much easier and quicker to have your loose items in your laptop bag than to empty all of your stuff into one of the plastic bins, then have to pick it all up again on the other side of the metal detector.
Syrreal is right, you can use your laptop during the flight, except during takeoff and landing. The captain will make an announcement after you get airborne that it's okay to turn on electronic devices, and another when the plane gets ready for descent to turn them off.
If you have a CD or DVD burner in your laptop, take some blanks with you and burn a copy of your pics in addition to saving them on the hard drive. This is just a paranoid precaution in case something happens to the hard drive while you are travelling home.
If you want to get online while at WDW, bring at least 10' long cables with you for either the modem (if you use dial-up) or ethernet (if you plan on using the WDW high-speed internet in the room). The phone or ethernet ports are not always near enough to the table or desk in a hotel room for a 6' travel-size cable to reach. Also, if you are using dial-up, save the complete list of local numbers for your ISP and the connection settings somewhere on your computer before you leave home, in case you need to troubleshoot the connection.
Don't forget your locking cable! I like to lock my laptop up by weaving the cable in and out among the wires of the wire shelf above the vanity in WDW Values and Moderates. Other hotels may have different places to lock the laptop.
