Vista 32 professional upgrade to vista 64?

I have a Vista 32 Proffesional installed on my Pc . The Pc I have can run 64 bit. do anyone know if I can upgrade to Vista 64 bit Proffesional on the same lisence? And where do I get the 64 bit version?

Thanks for the help

A key for professional, permits 64 or 32 bit use. You should have received a 32 and 64 bit DVD with your purchase of Vista. If Vista came preinstalled on your computer, you can get a DVD for free or for cost (about $25.00) from the computer manufacturer. Alternatively, you can borrow from a friend and then use your key when asked.
If your key number has the letters OEM in the body, you can use it only on the computer that the OS was installed on originally. If it does not have OEM, you can only have Vista installed on one computer at a time.

Good luck.