IIRC it took a few hours and I had no issues with it and it plays fine but I just made a post in a thread about CoD Deluxe digital download and the problems I'm having with the serial numbers I was given not working so something to think about. These are from GameAgent via Aspyr.
I also just read a post on another forum where a guy had invalid serial no. issues with his CoD 4 digital download from GameAgent but eventually got them resolved. I'm keeping my fingers crossed.
UPDATE:
Thanks to Aspyr I was able to get CoD Deluxe working, GameAgent was not very helpful