Hi Glenn,
Make sure that the treated posts are cured (dry) before you apply any coatings. If they were wet when you brought them from the lumber yard you should wait at least 30 days before coating.
I recommend an oil (alykd) based exterior primer for both treated wood and cedar wood. The natural oils in cedar make it unfriendly to paint so most people opt for exterior stain.
However, we have had success using an oil based primer and a high quality (water borne) Acrylic top coat. I would use the same combination for the treated wood.
Hope this helps,
rmichael / pro painter
