I am going to use my current 21 inch with my new 27 inch imac (coming when they offer the free ipod). I was told that there was a couple of ways to set it up but I don't know what they are. I was just going to plug it in and hope that it would just create more desktop to use. Is there a different way to set it up that you recommend I do or a program you recommend? I also don't know if having different size monitors would be a problem.