Why 320p? I say 3240 because the height res is 1080p, and I think you can comfortably tilt your head to get three times that height resolution. The horizontal guesstimate I made similarily.

edit: ah I see, I hadn't factored in the warping of the optics, if you're correct then the effective resolution would only be around 900p so I'm being too optimistic :)

Oh you're factoring in head movement. I see. Well you still haven't accounted for the warping that the optics do. They stretch that 1080 pixels across a 100 degree vertical field of view, so the pixels directly in your sight (not including peripheral vision) is really only about 320.

Funny coincidence, the oculus has a similar appearant resolution as the vanilla doom game on the crt's had.