Centering Pop-up

I got XML Gallery working but now when I use

on (release) {
getURL (“javascript:openNewWindow(‘products.html’,‘thewin’,‘height=500,width=340,toolbar=no,scrollbars=yes’);”);

it pops up uncentered, and off to the left a bit, and is still scrollable with the scroller on the mouse even when i set scrollbar = no. Anyway to center it and not allow it to scroll?

thanks ahead