I could care less about Modern Warfare just give me the Hard-drive.
Unfortunately, they're not going to sell the hard drive as a standalone thing. I think it's probably just a test to see how many people get it and maybe release it sometime next year.
Really, it's an AWESOME deal. For 400 bucks, you get the console, a 250GB hard drive, the game, AND two controllers.
And Modern Warfare 2 will be awesome.