The fastest way is a cab which will run you somewhere between $15-$20 and take about 15-20 minutes. Using Disney transportation you will want to take a bus to Magic Kingdom and then either take the resort monorail or the boat to the Poly. Travel time for that could be up to an hour or more depending on your wait for the bus.
Either a car or taxi is by far the best route. Taxi will cost you about $20 and it will only take about 15-20 minutes to get there. If not, the fastest way is to take a bus to MK and then hop on the resorts only monorail to Poly which is the 3rd stop. Depending on the time of year you're going and the wait for a bus/monorail it could take you anywhere from a half hour to 90 minutes. I'd give yourself a good 60-90 minutes buffer time if that's the route you choose.
In May, it cost me $16 to get to the Contemporary plus tip. Taxi is the best way but if you do not want to spend money, the bus/monorail is fine, just leave yourself enough time.