Sound like a jacked up truck with big mud grip tires, don't they?  I think you will be fine what ever you replace them with, as long as you rotate your tires every 5,000 mi.  The ford mechanics I've talked to said the rear tires tend to cup since they don't have a lot of weight on them, and have not had much success at getting tires that have went to long between rotations to quiet back down. 
    
I think those continentals  are noisy to begin with, but if you don't keep your new tires rotated often you will hear this problem again.