Apparently I was mistaken about downgrade rights on OEM preinstallations and that OEM preinstallations do have downgrade rights:

http://www.microsoft.com/oem/en/licensing/sblicensing/pages/downgrade_rights.aspx#fbid=NbRYestewy2

Apparently, every Microsoft licensing rep has also lied to me for the past 10 years because my previous post was right out of their mouths. To downgrade OEM preinstalled operating systems I have always been forced to purchase SA "for downgrade rights" regardless of the size of business I was dealing with. Looks like I should be able to get a metric * ton of money back.

* Update: from URL above: Other OEM Windows 7 versions (for instance, Windows 7 Home Basic and Windows 7 Home Premium) do not include downgrade rights. Apparently, only Pro and Ultimate OEM installs get downgrade rights, not the home editions, which makes sense.