Ie 7 beta 2 pop up question... thanks

hi all

i have installed ie 7 beta 2 and now my test site wont show up using the centered popup code covered at kirupa the link is
http://www.kirupa.com/developer/flash8/centered_popup_window.htm

bit stuck and wondering now because micrsoft have gone with copying firefox’s tab browsing how to get this working as when i click on the button it will open my popup window in a new tab and not a popup window.

works fine in firefox still.

hope that makes sense