If you drive 75-80 mph or less, it will take you 1 hr to 1 hr 15 minutes to go from the airport to WDW parking booth. That is if you hit no traffice backups - depends on the time of day. You can get there faster if you speed even more. The speed limit from Tampa I-75 to Lakeland (half way point) is 70 mph. Many folks do 80-85 between Lakeland and Orlando, but beware of FHP. They sometimes hide in the median (lots of 30+ ft trees!). It really would be a shame to start off a vacation with a $100+ speeding ticket! Plan for 1 hr and 15 min and you may be pleasantly surprised.
Note: You can get directions to WDW MK parking by putting in Car Care Dr as the address and Lake Buena Vista, FL as the city/state on your destination. This literally puts you at the parking booths (ka-ching! $6, please). From TIA, your trip to MK is 79.5 miles. Through Tampa is 50 mph, Tampa to I-75 is 55 mph, I-75 to Lakeland is 70 mph, Lakeland to Orlando is 60 or 65 mph. Disney is 35 (but most folks keep it up to 55 or 60). Yahoo says 1 hr and 57 minutes.
OH - saw 2 sherriffs clocking people last weekend at the entrance to MK - next to the split for MGM. One had someone pulled over. They hide behind the big Tower of Terror display in the median!
Have fun!