Do you mean the AMD Phenom II X2 550? Newegg LINK - click it
If so, Yes. AM2+ and AM3 CPUs fully support DDR2-1066 memory. (Mind you, the X2 550 is an AM3 CPU, not AM2+ CPU.) It's the older AM2 CPUs (Athlon X2's) which do not support 1066 speed. They can only run up to
DDR2-800 memory speed.
Just make sure you're purchasing an AM2+ socketed motherboard to go with DDR2 memory, or an AM3 board to go with DDR3 memory.
Oh, and you may want to double-check the manufacturer's website for the board's CPU support list. Many boards will require a BIOS update for full support of new CPUs.