Another Steam/install problem..7 hours download, really?

[gkhorse]

Sorry folks, I searched but didn't find an exact address to my question but I apologize anyway because I KNOW I can't possibly be the first with this particular question/problem. Help appreciated.

I have the DVD disc of COD. When I attempt a first time install from the dvd drive all goes well quickly enough and then I get the Steam gray box that gives me the check box 'option' of 'play game when ready'. Then it begins a 'download' that tells me will last approximately 7 hours and 15 minutes...thereabouts. I don't understand. Opening the disc appears the sim is on the disc. So, what exactly am I downloading for 7 hours and 15 minutes? What am I doing wrong or what do I need to do?

Thanks for taking the time to help.

[FenbeiduO]

maby(I have read from somewhere) when it begin to download(like0.1%) then you pause the D/L and go to the steam game folder(I dont really know where it is) paste the hole CLOD game files(which you have installed from the disk) to the dictionary.and then restart your steam,go to the installed game.try to find CLOD if there is one.