In addition to informative Solutions 1 and 2, I would add my advice:
Your design pop-ups the new window (or possibly a new tab). Such pop-ups often irritates the users; first of all, because the abuse of many advertisers' pop-ups, but also because they are pretty inconvenient in general. Therefore, many users block such pop-ups, usually using some browsers' plug-ins. Your work will look much better is you simulate the modal behavior you need using on-page modal dialog, like the one found in jQuery UI:
http://jqueryui.com/dialog[
^].
There are many 3rd party plug-ins offering good number of useful effects, such as dimming of the rest of the page, and a lot more. Please see:
http://bit.ly/1EKp8je[
^].
—SA