From IE> Tools> Options> Advanced> Browsing> uncheck "Reuse windows for
launching shortcuts."
Two more ways to control window usage:
1. Drag the link to the window you want to use (sometimes inconvenient.)
2. Drag the link to the button on the taskbar of the window you want to use
(don't release it yet) wait a second for that window to restore and take
focus, drag the link to the window.
Hope this helps,
Don