In a shocking and completely expected turn of events, the "get a PC with Vista and get a free upgrade to Windows 7" offers that have been trying to convince people not to wait till Windows 7 is released to buy a new PC, can come with some Hidden Fees. Some pretty hefty for a DVD being shipped out to you. As I understand it, it's a free upgrade from Microsoft as far as they are concerned, but if you get it from a PC manufacturer (ie: Dell, Lenovo, etc), they basically get to charge you what they want for it (in the form of "service fees").
So either wait till after all the super-cool Windows 7 launch parties are done before buying a PC, or be careful and find out exactly what you get for free or not for free. Or download a real free OS.