Some guy on the forums said,
Besides, with Vista the CD key could be used for 32-bit or 64-bit installations. The keys weren't separate like in XP.
Can I technically change my 32-bit Windows Vista OEM machine into a 64-bit one without having to buy a Windows Vista 64-bit copy?
I've always thought that I would have to buy another Windows version to get myself into 64-bit (just like in winXP).
Edit: after googling (which I should have done in the first place), the aforementioned is true! HUZZAH!! HERE I COME 4GB OF RAM!