PC sales are the smallest part. The success quoted here is based on first week sales only. Lets look at this after a few months and see if its still selling strong like COD4 was.
I believe the stong first week sales is due to a very succesful ad campaign and lots of media hype. Controversy also draws in attention too.
I was going to purchase this but after discussing it with other players while playing cod mw online i will wait for it get cheaper first. ie hit platinum.