Clip Art copyright issue?

What kind of artwork (eg illustrations of children's books), and clip art are considered "public domain"? How do I know if a copyright has expired? If you take a lot of property not clip art and illustrations and a compilation is a "new" piece of work and can be resold for profit?

I found a couple of links to help you to follow: http://www.copyright.gov/records/ – Search Copyright Records http://webclipart.about.com/od/msub67/ – Copyright Information and issues related to hope clipart it helps!

Megadeth-Hangar 18(Studio Version)