If you have your own laptop you will have HISA at the Poly, it is $9.95 for a 24 hour interval or you can do dial up for the local call fee (75 cents per connection...just make sure you have a local number as the central Florida area is weird in that even though it is the same area code it does not necessarily mean that it is local).
If you need to use an on property computer you can go to any of the Buisness centers located at the conventions resorts... Yacht and Beach (8am-4pm daily), Grand Floridian (7am-5pm Daily), Contemporary (Mon-Fri 7am-6pm, Sat-Sun 7am-5pm), Boardwalk (8am-4:30pm daily), Coronado Springs (Mon-Fri 7am-7pm, Sat-Sun 7am-5pm). You can use the computers during regular buisness hours, the pricing is subject to change but right now it is $10.00 for 15 minutes or $40.00 per hour (each 15 minutes used is pro-rated so if the guest is on the computer for a half hour it is $20.00)