I have a 2009 iMac 24 inch, and a 2010 27 iMac, and a mini-display-port to mini-display-port cable. Plan A would be to use the 24 as the second monitor. However, I gather that the 24 has only output not input, so that would be impossible. However, I have also heard that with a certain program it would be possible. 1. Can the 24 be used as a second monitor? If so, how? 2. Alternatively, the 27 can definitely be used as the second monitor?