It has been widely reported that in Europe the pre-order version of Windows7 E will be a full version.
However, according to the FAQ posted by Microsoft UK
http://www.microsoft.com/uk/windows/buy/offers/pre-order-faq.aspx
So it seems that the "Full Version" isn't a complete stand alone full version, you must have a prior copy of XP or Vista "running" to use it. i.e. you must be upgrading.
Unless, of course, Microsoft UK have just copied the FAQs from Microsoft USA where the pre-order version IS an upgrade.
However, according to the FAQ posted by Microsoft UK
http://www.microsoft.com/uk/windows/buy/offers/pre-order-faq.aspx
To be eligible for the offer, you need to be running a genuine copy of the Windows XP or Windows Vista operating systems
So it seems that the "Full Version" isn't a complete stand alone full version, you must have a prior copy of XP or Vista "running" to use it. i.e. you must be upgrading.
Unless, of course, Microsoft UK have just copied the FAQs from Microsoft USA where the pre-order version IS an upgrade.