you can paint just about anything...the trick is to balance the prep and materials choices. Some light sanding and primer and you should be good to go.

KMS Woodworks, great response. Thanks!!!

I would also suggest to use a clear latex based Polyurethan top coating for your desk top. It helps prevent scratch marks and is easy to clean with simply using water and a rag or sponge. Several coats of this would make the desk top surface wonderful.