I made a similar decision recently and decide to go with the C2D. The 802.11n is good for the future, as is the DL Superdrive. One benefit you haven't mentioned is the 4MB L2 cache in the C2D.
Still, if money is tight, I'd say that the CD is a very good buy.
Also, all the 2.0 GHz Macbooks come with Superdrives.