There should be a make and model number stamped on the Mother Board some where. If you find it just Google it and look on the manufactures webpage to see what CPUs it supports. You may need a BIOs update for some which should also be on their page.
I think the motherboard supports that. My motherboard's a G33 chipset.
Great then I would go for the quad core over an extreme addition dual core. You will see better bang for your buck.