Uh oh, now you've confused me. The board does use DDR2 memory, right? AMD made their AM3 processors so they will work in AM2+ motherboards. Unfortunately, motherboard manufactuers like to use this fact to label their AM2+ motherboards as AM2/AM2+/AM3, but in reality, its just an AM2+ board. The memory is the key. If a board uses DDR2, its AM2+, if it uses DDR3, its an AM3 board. I just want to make sure I'm not leading you astray.
My answer is still the same though, your AM3 processor will run DDR2-1066 speeds, as long as your motherboard supports both.