The part of I-Drive that Vistana Villages is on is not congested. I-4 should be a problem on a weekend (little commuter/rush hour traffic and most of the traffic that will be there will he headed toward Disney rather than away from it as you'll be going.
Left out of the resort onto I-Drive.
Continue south on I-Drive for about two and a half miles.
Get into the right lane and bear right.
At the traffic light go straight across the intersection and continue on World Center Drive.
For Universal turn onto I-4 east just after the Marriott World Center Hotel. It's about 7 or 8 miles to exit 75A. Get into a left lane and turn left from the exit ramp onto Universal Blvd. The parking garages are just ahead on the right. [The other choice for Universal is to go right out of the SVV resort and go north on I-Drive to SR 528 West (about 3 miles) to I-4 East (about 3 miles to exit 75A). Might be three or four minutes less that way.]
For Epcot continue on World Center Drive, which becomes Epcot Center Road once you're on Disney property, and follow it to the Epcot parking lot.
For DHS also follow World Center Drive and continue about a mile or less beyond I-4 to a right exit to Buena Vista Drive (Epcot Resorts, DHS, etc.) - it's the second of the two exits right after I-4. And then just follow the signs to DHS on the left.
Lots of very good signage for all of these theme parks.
Dick Taylor