I have had a look in to this system for you and also the part numbers you have listed. This system does indeed take DDR2 memory.
The part you have ordered is actually DDR2-667 and not DDR2-800 as you have advised, I'm basing this from part number CT25664AC667.16FHZ which you have listed.
However we do recommend that this system will also support DDR-667 so the memory you have ordered will be compatible with your system.
When you order memory against a system the part number is changed, so if you ordered CT25664AC667.16FHZ against the Aspire One D260 it would be part number CT1358784. This is so we can keep track of what memory has been sold against what system.
I can confirm the memory you have ordered will work with that system.