Memory compatibility

I have a new Inspiron 1720 that I bought with 2GB of RAM because of the initial huge price for 4GB. Now, I am thinking about buying the 4GB, but I need to know if the RAM from this system would work in an older Inspiron 8200. I know that the speed of the new memory exceeds the needs of the older 8200 system, but the question is: Will it work from the voltage and form factor point of view? Thanks!