Hi newcomer and welcome to the Tom's hardware forum.
What exactly model of Acer desktop do u have?. But if the rig is currently using DDR2-800, is almost sure that support DDR2-667. BUT bear in mind that if you install 667MHz with 800MHz, the speed of all your RAM will be the lower speed.
Thanks so much Saint19. I will install the mem and let u know how it works out!
I am currently stationed in the middle east and the tech help here leaves much to be desired , so this forum is a godsend. It's safer for mr to do my own maintenace on my computers. Thanks again! Pam
My mem is Working!!! Yippeeeee!!!! I am so happy! Thank you so much! And certainly this site is bookmarked for me. Love it! If you take a computer in for service in these parts...most likely you will end up with pirated software and counterfeit parts, so I am so happy you could help me work this out. Take care!! pam