i think it would be worth it, you will still have 2gb.
however, i know that it would be much more beneficial to save an additional 100.00 and get the 2 x 1gb kingston sticks (or see below).
i think that is your best bet, and certainly you will notice a tremendous difference with it versus 1gb.
you will see a performance increase with the 2gb in single channel. however it will not be nearly as significant as running the 2gb in ddr mode.
consider this choice, g.skill ddr400, only 175.00:
