If they are ddr3, they likely will work.
1066 is a bit slow, but performance is not proportionally impacted.
Go to the ram vendor's web site and access their ram configurator.
Enter your motherboard, and you will get a list of supported ram kits.
If you bought two individual sticks, they will not be supported.
Ram is sold in kits for a reason.
Ram from the same vendor and part number can be made up of differing manufacturing components over time.
Some motherboards can be very sensitive to this.
That is why ram vendors will NOT support ram that is not bought in one kit.
Although, I think the problem has lessened with the newer Intel chipsets. Still,
it is safer to get what you need in one kit.
If that is your situation, I would consider returning the ram and buying a supported kit of 1600.