I know you can't upgrade from Xp/Vista to Win7 (i.e. you have to perform a clean install), but take note, if you read carefully, it is apparent that this is the upgrade version of the product, not a retail version.
If it is the upgrade version, it will likely require proof of ownership (i.e. your previously activated XP/Vista CD Key or the original installation media) to activate/install Windows 7.
According to the requirements on Amazon, it states that 'Windows XP or Windows Vista' is required.
If you check out the FAQ on the Microsoft Windows 7 pre-order site, it also says 'How do I know if I am eligible for this offer? To be eligible for the offer, you need to be running a genuine copy of the Windows XP or Windows Vista operating systems.'
If you don't already own a copy of Windows XP or Windows Vista, don't be surprised if you can't install or activate this software.
The European court has ruled that M$ cannot supply upgrade versions in the EU, due to some silly anti-trust legislation.
So you can be 100% sure that the version you buy is 100% full retail.
(Except, of course, the fact that NO web browser is installed in the EU when you install Win7 - again owing to the anti-trust thing - so make sure you have a copy of Firefox on a USB stick or a CD before you do the install!!)
It's supposed to be hardware dependant I think, being able to run a form of Windows XP inside Windows 7, I admit I dont understand all that well but from what I've read.. If thats the case, they are probably marketing this version for those with higher spec PCs and thus want to do more with their computer.