Ok, I want you to use this link:
http://www.sofotex.com/cgi-bin/ls/page.cgi?p=download&d=1&ID...
It will prompt you to download a program called aida32. Aida32 will tell you a whole bunch of stuff about your PC. If you curious about your PC it's a great way to find out about it.
What you are most interested in is what motherboard you have, the mother board will determine what memory you can buy.
After you install and start up the program look at the upper left side of the scrren. Click on summary, it's under computer. Post the name of the motherboard name and
the motherboard chipset and we can find out what memory you can buy.