paint works, but clean it first REALLY well.
a think sheet of laminate can be glued over it too and trimmed to fit nicely...
wall paper will not hold well to that wall board, unless it's vinyl and spray glue is used...
all of the true things that i am about to tell you are shameless lies. l.b.j.
we are here on earth to fart around. don't let anybody tell you any different. k.v.