Sisoft sandra lite 2007 is a good analyzer of systems. Belarc is somewhat ok but never trusted it.
Anyway if you have downloaded sisoft then run the program and click on cancel the "tips" popup. Save for later when you get to know the program better.
Click on Hardware tab>>click on mainboard-mainboard, chipset..etc tab icon and wait for analysis. This will show motherboard manufacturer and model number etc if you wish to use Crucial to define your ram.
Download and run. On left pane expand motherboard and look for SPD. Click on SPD and that will give you info on your ram. Strongly suggest that you confirm with Crucial, if you can manage it, then you'll be sure which ram modules to buy.
I bought mine off the infamous ebay for half the price and they work..:) Good luck.