Does anybody know a good way to protect a data cd full of .pdf files?

[unknown_g]

I'm looking for a way to protect a cd full of .pdf files in a folder on a cd. a couple of ideas i had was to stop someone from copying the files onto their harddrive or any other media but allow them to look and use them on the cd in a cd-rom. any tyoe of downloading would be prohibited.

another idea was copy protect the copy, but i don't know any real way to do that. i wanted to also stop them from copying the cd.

anybody know of any programs i can use?