Do you know what kind of motherboard you have. If you don't, look inside there should be a number somewher like P4P800, AN7N8, GAG7N, etc. Once you get that number then you can search for it on the web and find the home page. From there you can find out what you have.

or

Go here www.belarc.com/free_download.html download this free computer tool that tells you what you have inside your PC. I think this would be your better choice.