Karen, I'm not a painting specialist, but from my experience you would be better off with a good coat of oil based primer. First, sand thoroughly, including the details, then wipe clean with a tack cloth or lint-free rag dampened with solvent.

As others have said, Mr. Clean Magic Erasers work quite well without compromising the integrity of the wall finish.

Please do yourself a favor and don't beleive "paint and primer in one". All that refers to is painted surfaces that have minor stains or a large color change. There is a reason that every paint store carries numerous primers. That being said, I echo the thoughts of the previous participants and say to use an oil primer that is specifically a stain blocker. These smell very bad but the smell will dissipate quickly and can usually be recoated in an hour.