I have bought the retail version of windows vista 64 bit. I want the 32 bit version, and I read from somewhere that I can use my 64 bit product key for ordering the 32 bit cd-s. Order Windows Vista CDs - Microsoft Windows this is where I'm trying to order the cd-s from, but when I type in my product key found on the back of the dvd box of the 64 bit installation, it says my product key is invalid. What should I do ?