It works fine for me in IE7. It's slow, but it works fine.
But, why do you need to open 5 windows? One pop-up window is annoying, and having more than that would probably be a huge mistake with regard to user experience.
Also, you need to the new keyword in front of Array, so:
var Win = new Array();
Actually, it would be much better to use an array literal instead:
var Win = ;