Use Subwoofer crossover or processor crossover?

In your home theater setup, do you use the crossover in your processor or do you use the subwoofer crossover? Do you disable one and just use the other?

I use a Sunfire Theater Grand II processor and a Velodyne DD-18 subwoofer.

My whole system is posted below.

I'd like your opinions on which one you use and why.

...thanks, mitch