I have a Dell Optiplex 745 SFF with 2 x 1GB RAM, I want to add another 2 x 1GB RAM to bring it up to 4GB to run Win7 Pro 64-bit.  I ordered some RAM off the internet but when I tried to fit the RAM the modules look like they are about double the height of what I currently have fitted.  They look like "normal" height RAM modules that you find in tower desktops.  I think because of the smaller space the SFF model seems to need a smaller height (looks like same length) RAM module.  There is physically not enough space to fit the "normal" height RAM modules.

Does anyone know the exact type of RAM module I need to fit in a Dell Optiplex 745 SFF?