I'm with them, you really shouldn't drive it until you figure this out. If you had to add water to the system to bring it up to the correct level then it's probably not condensation. Still, like Randall said, when you use the A/C the Boxster leaves a huge puddle under the car in the area you are talking about.
Take it to a dealer or at least a Porsche independent mechanic and pay them to figure it out if you can't do it or don't have time. You'll be glad you did.
