Hi Preece,
You cannot upgrade from within a 32 bit Vista to a 64 Bit Vista. You will need to run the 64 bit Vista from bootup, but like doing a
clean install of a upgrade version of Vista. Try the method at this link and you should be left with a clean install of the 64 bit Vista.
- How to Do a Clean Install of Vista From a Upgrade Version
Do not forget to backup anything you do not want to loose on a separate media other than the hard drive you are installing the 64 bit Vista on.
Shawn