I have a 27" iMac i7 that I would like to hook up an external display to. The problem is, and maybe I just don't understand Macs enough, that I can't find a "video out" port. This is what the back of my iMac looks like (the one on the right): Audio in, USB, FireWire, Thunderbolt and Ethernet... No mini display port, no mini DVI, no VGA, nothing. I'm reading other forum posts about people doing this, but none mention how they did it! What am I missing?