Just have a look at the source code:
function data() {
window.open('URL','NAME_OF_THE_WINDOW','toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=no,resize=no,width=778,height=400')
}
(play a bit with the size and the different commands...)
Make a link to "javascript:data()" and your window will pop up when someony clicks the link.
- Tobias