Small Biz accounts can ask for the CDs after the sale, and they arrive by FedEx the next day, no charge. Or at least that's how it has worked the last few times around for us. (Note that those CDs are still in the shrink wrap in a box somewhere here, for if/when we discard the machines at EOL)

Non-Biz customers get dinged with threats of a fee for the same service. Some machines can be configured with the discs for extra $$ at purchase time, too.

EDIT: Oh, and there's a way to burn a single OS disc from the recovery partition contents now, too. That's Dell's preferred way of doing it.

Cheers