Going another way, I find that there are two different subsystems on the eMachine E725 - one which takes DDR2 ram and one that takes DDR3 ram. Makes for difficult advising here since they are in no way interchangable.
Because of that - I'm going to refer you to Crucial's Memory locator page where they have a tool "Scan my System" which will tell you which type of ram is correct. http://www.crucial.com/store/drammemory.aspx
Another option to determine which ram is right is by running a program called Speccy. Available free here http://www.piriform.com/speccy
Speccy will tell you all there is to know (and stuff you probably don't care about) about the hardware within your machine (including memory)
Run either of those and you will then know for sure which type of ram your laptop uses