gollum, I ran some quick tests under the circumstances you mentioned (flat ground, head on- charge, unfatigued, and no valour or bonus armor) with three different types of cavalry against the camels, and the results were these:

Feudal Knights - Bedouin Camel Warriors: Camels won, killing 24 knights and losing 3 men. (in this test feudal knights used wedge formation when charging and the camels didn't.)
Knights Templar - Bedouin Camel Warriors: Camels won, killing 25 knights and losing 9 men. (both in wedge)
Kataphraktoi - Bedouin Camel Warriors: Camels won, killing 32 men and losing 15 men. (camels in wedge, kataphraktoi wasn't.)

I think these results aren't absolutely waterproof since I ran every fight just once, and maybe once in a while the knights might win, but still it seems that camels really have the advantage when fighting in the desert, even in a "fair" fight. I have to admit that I was pretty suprised by the fact that Templars went down that easily.