Help, Plagiarism and Prosecution!?

Hey, I wish to sell a cheap information product on ebay comprising 100 game guides burned onto a CD-R. What are the laws regarding this? Is it automatically clified as Plagiarism or does the piece have to be copyrighted? I saw that someone just scanned the official GTA IV guide and is selling it on ebay and there does not seem to be any reprecusions. M