>The first thing I would do in the situation of the original poster would be to get an attorney and register the copyright with the federal government. The advantage of doing this is that if the client contests the ownership fo the copyright then, when registered, it is the burdon of the client to prove you don't own the copyright. If it is not registered then it is your burdon to prove that you do own the copyright.

My understanding is that if you hold a copyright you can sue for only actual damages. If you have a registered copyright, you can also get punitive damages, which my be several times any actual damages you could suffer. This was part of a one day class on intellectual property I attended four years ago.