I am, thank God, not a lawyer either, but I suspect the initial question was much simpler than what has been adressed since.
As "public domain" scores are more or less the opposite of commercial scores, copyright claims mentioned on them (such as the cpdl license or CreativeCommons) are IMHO not so much about financial gain as they are about recognition. So, ebjcr, your copyright notice is basically up to you, as long as you're willing to give credit where credit is due. Putting (or leaving) it on the scores you copy is nice, but as an editor, I'd be even more appreciative of a mentioning when you perform the scores in public - an extra line in a program leaflet or the like.
Use this forum for HELP at Choral Public Domain Library as well as FEEDBACK