So I'm one of the many that is soon making the switch to Mac. I love the OS and the iMacs are gorgeous to me. So I'll be buying sometime in the next couple months after I get my finances situated. Here's my question: I currently have a terrible PC now, but I have a nice 20" Dell flatscreen Monitor. Would I be able to use this as a second dual monitor? Or would it even be worth it? My other option is sell it, but if I can use it as a 2nd monitor, I might prefer to do that? Would the quality be a lot worse as well?