I have an old VGA monitor that is 21" and I don't use anymore. I have a firewire port on my iMac that I barely use. The idea is to connect this VGA monitor to this firewire port, so I can have a third monitor on my iMac. I need this VGA monitor to display at least 1280x1024 pixels (its maximum resolution) with at least 70 Hz. Is there a way to do that? thanks.