As Tom suggested above, the Mears calculator is helpful. Back in May, I took a taxi on a Sunday morning from the Orlando Airport to the Swan (over in the EPCOT area), and it was approx. $62 (before tip). Most of the time, they take State Road 417 (Florida Central GreeneWay) route.
You may also want to check the Ground and Air Transportation forum on this site, as there may be more information over there.
Spend a few extra dollars and get a car service that will meet you at the bottom of the escalator, collect your luggage for you and also make a courtesy stop at Publix on the way to your resort so that you can stock your room with beer, wine, water, snacks, sunblock or whatever other life support you may need for the week. The money you will save not buying these things on-property makes it well worth it IMO. We usually use Quicksilver Transportation.