Yeah, get another stick of ram. Download CPU-Z from www.cpuid.com
to find out what ram you need (Most likley DDR) post a screen print of it.
I don't really like Corsair, but it is still good.
DDR2 is what the newer intels are using, and it is really isn't good, as it has higher latencies, than similar speed DDR, and DDR can be faster.
DDR2 has a higher bandwidth, but it is not really worth it, as a AMD 64 with DDR ram will have better bandwidth because of the Hypertransport. Do a search for more info.