Agreed, the ram is something I would address as soon as possible. I am assuming you're using DDR2 because of your motherboard, if so DDR3 is much cheaper and faster and easier to find as well. Considering the age of the mobo, it may be worthwhile to get a new one if you can afford to do so at this time.
Really you can get a lot more DDR3 memory for your money, think of the mobo as an investment on your future. Thats my recommendation.