If you need extra desktop space it doesn't necessarily mean that you have to buy a new monitor. I'm currently evaluation
multiple virtual desktops. Imo there is no big difference if you either turn your head or push a hotkey and switch to another workspace. For multi instrument/divergence trading this might be less than ideal, but there are ways to make this work as well.
... just a suggestion. The program I linked to is not the only one out there.