Windows 7 Full Install and NIS2009/10 License?

I have a 3 machine two year license to NIS2009.  When Windows 7 arrives (I have two copies on pre-order) I will be replacing Vista on one PC and XP on another with Windows 7.  As I am in Europe (UK) Windows 7 is NOT available in upgrade form only full install.

 

How will I re-apply the licensing onto the two existing PC's?  Is there a way to de-activate (like Adobe software)? To re-activate on the new installs?  I am hoping that I am not going to get some mealy-mouthed reply about these 2 PC's now being 'different' or 'new' PC's when clearly they are not?  The hardware will remain unchanged apart from massive memory upgrades.