Do I get Upgrade Version or Full Version?

I am currently using Windows Vista 32-bit and would like to upgrade to Windows 7 64-bit. I have read that I would have to do a clean install. I want to know if I need to get the Full Version of Windows 7, or if I can get away with the Upgrade Version.

But does that mean I have to get the Full Version of Windows 7?

He's asking is whether he can install 64-bit Windows 7 from scratch by buying the upgrade DVD. He doesn't want to buy the full DVD because it's more expensive and he already has 32-bit Vista.

So does the upgrade ONLY work from Vista-32 to Windows 7-32? Or does the upgrade also allow you to do a clean install using Windows 7-64?

It's a good question, I'm sure there are a lot of people who would be interested in the answer...

Yes you can install an 'upgrade' from scratch. Going from a 32bit OS to 64 will force you to format the drive of course. I believe all you have to do is put in the old OS's disc to verify you own it and possibly enter its CDkey to make sure it's 'genuine'...
Someone please verify this for me?

Wait get the OEM version and do a clean install of which ever version.

I think megamanx00 has it right.
On advice from Microsoft support, that is the procedure I used to change from vista home premium 32 bit to 64 bit. The procedure is necessary because the 64 bit upgrade will not run under a 32 bit os. Presumably, Windows-7 will be the same. It does bring up an issue though, Why buy the full retail package when the upgrade package costs half, and will work, albeit a bit more clumsily? The upgrade vista version is considered retail and entitled to microsoft support. I think this is an issue that applies to few enough users that microsoft will not address it. Solutions that I can think of will cause more confusion than it is worth.
Net: the OP should do fine with the upgrade package.

Plan on a clean install anyway. No sense in carrying forward some old junk in the registry and elsewhere.

I think you are mistaken here. The OP is going from a 32 bit vista to a 64 bit windows-7. I don't think that change can be done in place. At least in the case of vista-32 to vista-64 it would not work. The upgrade in place needs to run on a 64 bit os to upgrade in place to a 64 bit os.

I think it is a moot point, though, if you can manage a clean install.

So what happens if there's a glitch after the drive is wiped and before the new OS is installed? If you have to restart the installation there's no old OS for it to detect...

That's a good find, and it's the way I'd expect it to work. Asking for the CD-ROM is kind of useless as you can borrow almost anyone's old CD if you need to. The product key is the real proof of ownership.

So if this is true then it means that the answer to the original poster's question is: No, you don't have to buy the full version - you can buy an upgrade version and do a clean install of 64-bit Windows 7 as long as you have the disc and license key from your old 32-bit Vista installation available.

Do you suppose that the old XP or vista key will be recorded as never to be used again?

What if windows-7 does not work for you and you have to go back to the old OS?

The key is the most valuable thing you get when you purchase a copy of Windows, no matter how you've purchased it. The key should be protected even more than the media. For example, you should never let anyone else know what your key is - if you do, they could use it to call up Microsoft and get their system activated, and you'd loose your activation status.

Most pre-built systems have a decal with the Windows logo and the key on it. Retail versions come with such a sticker, although I've never actually put in on any of systems.

I scan the key so that the scanned file ends up in my extensive set of onsite and offsite backups.