If this other website is in the US then it is very easy for a lawyer to pursue. A good internet lawyer will even take this on a contingency basis because the money for the infringment is quite good.4) Contact a copyright lawyer and ask for legal advise on possible action. While often difficult to pursue, penalties for copyright violation are severe.
Also, start taking snapshots of this other website pages daily. The copyright infringments are daily fines.
And yes, I say hang 'em high.