I bought Windows 8 Pro on Microsoft's promotion. I used upgrade assistant while installing and it got to 90% and stayed there for an hour and a half until I cancelled it. It didn't respond, so I ended the task and retried. It did the same thing, and then it wouldn't start, so I sought help. $150 later and after the deletion of anti-virus and anti-spyware it is now installed, but a majority of my apps don't work properly. So I went back to tech support only to determine that I had a 32-bit version; I was already using Windows 7 64-bit so how do I now go to 64-bit?
You need to clean install the 64-bit version. You cannot upgrade from 32 to 64-bit. The Upgrade Assistant will also not download the 64-bit version if you run it from within a 32-bit OS (or vice versa).
I suggest you get the 64-bit version on a 64-bit PC, then use the option to create install media on USB/DVD (ISO). Use that to boot from, format, reinstall the OS and all your apps and finally copy your personal data back from a backup (I know it's a lengthy process, but the best thing to do is start afresh from a clean slate).
Edit: On a second read, your post seems to imply that the Upgrade Assistant downloaded and installed Windows 8 32-bit onto Windows 7 64-bit? That is just not possible.