Simple jQuery code snippet to add an event to all links with class .popup to open in a popup window instead of the current page or new tab/window. Specify the heights and widths as you please.
jQuery(document).ready(function($) {
jQuery('a.popup').live('click', function(){
newwindow=window.open($(this).attr('href'),'','height=200,width=150');
if (window.focus) {newwindow.focus()}
return false;
});
});