Maybe you could use the CrucialSystemScanner.
Link
I have used it every time I needed to increase the memory available for the system to it's max..
The only things I get of this site is then:
Type of RAM (DDR2, 3 and/or SODIMM etc.)
Maximum (In GB over all slots)
Speed (noted as PC(#-)#### and/or a (#)###MHz value)
CAS latency (CL#)
and Voltage (between 1,5V and 1,9V I think)
After I know what I need through this utility, I simply use those values to shop for the best RAM where I think it's sold Cheapest.
