AA is a function of the raytracer sampling. There is a rollout in the raytracer section of the Render Window for AA quality. Not sure what type of filter C5 uses, and I don't think there is a selection for different filter types; I'm guessing Box or Gauss filter.

The object, shadow, and light accuracy settings would also affect the AA of the final image.
If you have Pro and can set the raytracer RPP; higher RPP sampling yields more accurate AA.

A scanliner's ability to AA is very limited, compared to a raytracer's. C5 has both; and a third sampling method too, the photon mapping(which is only fully effective when using the raytracer at the same time).
Basically speaking, more samples = more accurate AA. More sampling methods = more accurate AA. Maybe DAZ'll put FG (Final Gathering) and/or Supersampling into C6 or C7.

EDIT - prode could resample that large image size down with Photoshop or some other Image Editor and let that do the AA. PS does good AA resampling.

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