[carpeperdiem]

First, this is not a COPMPLETED custom mod, so I'm moving this thread to template editing.

Next, if you search the forum for "shadowbox" you will discover many of us are using it. You will replace the popup code with shadowbox code -- but that has already been discussed in other threads. The key is making shadowbox work perfectly on a plain html page, then use that code to replace the popup code in product.tpl - but that is beyond the scope of this thread... the other threads have already addressed this.

Good luck.