Of course Windows costs Dell money. There is an exact same Windows version of this laptop with the same CPU that sells for $50 more than the Linux version (see the fourth configuration in my link).
Or one could argue that Windows costs nothing to Dell, because they just pass the licensing fee (the $50) to the consumer.
Windows costs Dell money, but Windows+all the extra crap they're paid to install earns Dell money. Any price difference between Windows and Linux laptops is purely a marketing move.
Or one could argue that Windows costs nothing to Dell, because they just pass the licensing fee (the $50) to the consumer.