I have a 24 inch iMac from late 2006. model number A1200, it had a 250gb hard drive, 2.16 / 1 gb... so I am new to trying to do DYI computer stuff so bare with me. It needed a new hard drive so I bought a WD 500gb one and installed it. The computer then turned on and a blank screen came up with a file with a ?... SOmeone gave me the non working iMac so I don't have the original start up disk and not sure on the operating system but I have a macbook and I put in my snow leopard disk. So I got the option for english then I clicked continue and when it tries to install it says select disk where you want to install mac os x but nothing is coming up and only the back button is highlighted. Does anyone know what I can do? Thank you..