Content theft - need some advice

[In Omnibus]

Forum content is the property of the individual who posted the content. If it wasn't forum owners would be liable for the content posted by their membership, including but not limited to warez, child pornography, and content which violates 17USC107 Fair Use clause of the Copyright Act. Where you may have them on legal grounds is regarding infringement of intellectual property. The theme itself and any proprietary content would be subject to de facto copyright under creative commons or other similar licensing. Unfortunately, the only person qualified to give you legal advice is a duly licensed and retained attorney at law. While I can speak in generalities the rights, limitations and exclusions vary greatly from state to state, and there is no overriding law which pertains to the internet at large.

My best advice is to consult qualified legal counsel as to your specific available remedies.