what you should do l3ights is run everest on the computer you can download it from my site free.
www.davesdrivers.com/everest
download the trail version as thats a new pc and the old home version will get things wrong.
install and run that program.
with it running click motherboard in the left hand list and then motherboard again in the large box.
everest will give you a report on the motherboard.
please post that report back here so i can take a look.
with that report i should be able to tell you the best speed ddr2 to put in the system and what is the max you can put on the board.
now i did notice with that link you posted the computer came with vista are you still using vista ?
if so i will give you a little advice.
vista is a memory hungry pile of poo , it runs best if you have 2 gig memory , will run with 1 gig but will load that about 55% to 60% just to run windows leaving very little for anything else.