In theory, the amount of detail that can be resolved by the two cameras should be similar because, as you say, they have similar pixel counts.
In practice there will be significant differences. The CCD used by the D1x is far larger than that used by the CP5000. This gives it several advantages:
Firstly the larger size of each of the pixels makes the CCD more light sensitive and also means there will be less backround noise.
Secondly the lens has an easier job to do: the pixels of the CP5000 CCD are very small - probably smaller than film grain - so the lens has to be capable of resolving very fine detail to get best results.
DPReview has comprehensive reviews of both cameras, and you can download full resolution samples from the galleries so you can see for yourself how the two cameras compare.