Hi! I plan on buying a new laptop, MBA or cMBP, and since I have a 2009 27 inches iMac, I would like to know if I could use it as an external monitor? The new laptop will have thunderbolt port but my iMac only has a mini display port, so can I plug my iMac's mini display port in the laptop's thunderbolt port directly? Or do I need an adapter of some kind? What cable do I need? Thunderbolt-thunderbolt, thunderbolt- mini display port or mini display port mini display port? Man I asked a lot of questions!