Again, Thanks everyone for all the great information and support.

Met with the contractor on Monday and he was pleasantly surprised at
what he saw and found. so happens that the acoustic ceiling is not
really the acoustic ceiling that's everyone usually has, but it's
actually joint compound sprayed.

So my ceiling has drywall, then a coat of plaster with chickenwire,
then a coat of compound, then a coat of sprayed compound that looks
like acoustic ceiling.

Contractor said that putting a skim coat over this would be fine but we
insisted he remove everything to the plaster and use 1/4 drywall to
cover.

now everything looks great!

Thanks Everyone!!

T

p.s. found or made some cracks in the plaster so the drywall will
definately cover these up!!