Do I get Upgrade Version or Full Version?

To go from a 32-bit to a 64-bit operating system, you need to do a complete reinstall. Sorry.

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

The retail package of the upgrade and full versions will contain both the 32 and 64 bit dvd.

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...

I know that Windows XP upgrade discs don't let you install from scratch, and I see no reason why Windows 7 would be any different.

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?

Well you actually have to install Vista Twice, well at least you did when it first came out. I haven't used an upgrade disk in a while

http://www.whatthetech.com/2007/01/31/workaround-for-cl...

Anyway we'll see how it works for Win7 when it comes out.

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

NO you can use the upgrade as specified on the Microsoft site, however you will need to backup all your files as W7 will wipe the drive when installing the 64 bit version. Don't wipe the drive yourself, W7 will detect your Vista instalation allowing you to upgrade.

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.

There is no need to install twice when you have a valid Windows activated instalation.
We are not dealing with Vista, this is Windows 7.
Referenced from Microsoft:
"If you have Windows Vista, you can purchase Windows 7 Upgrade versions. You can do a clean install (back up your files, clean install, and reinstall your applications) or an in-place upgrade (Windows 7 installs over Windows Vista). "

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.

If you read my original post I did say that a clean install will be needed for 64 bit version.
The previous post was in reply to megamanx00 post stating the need to install twice using a reference to Vista. The point was, to do a clean install with W7 using an upgrade dvd, a double instalation is not required when a valid Windows OS is found.
You can in fact use the upgrade disk going from Vista 32 bit to W7 64 bit. That is not the same as doing an in place upgrade
As I stated previously you use the upgrade disk to do a clean instalation of W7, it will detect the existance of Vista and then wipe the drive.

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...

Apart from reinstalling previous OS, at this stage no definate answer is available as far as I know. There are some that say you can insert the OS disk for verification, others that say that a installed and activated system is required.
I havn't been able to locate anything on the Microsoft site to say how it will check for previous OS other then as stated previously.
Some are assuming that the old Vista dual install will work, at this stage I have not seen any confirmation to that effect. We will have to wait untill someone lets the cat out of the bag.
There may be some leaks once the RTM's get out to the tech community.

Update
Just found this on Windows 7 Forums
"Windows 7 upgrade will be able to do a clean install as long as you have a valid and legal copy of Windows XP or Windows Vista to show during the install. A prompt will appear asking for the cd-rom and product key.
Jessica
Microsoft Windows Client Team "
Apparently she works for Microsoft.

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.

Where people may get into trouble is when they loose the original key, as some toss the old disk and key somewhere and then can't find it.
Everyone will need to make sure they have the disk and key readily available.
I put my key in a text file and burn it to cd/dvd with other backups and also keep a printed copy, I have trouble reading some of Windows Key fonts anyway.

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?

...then you can activate by phone. Takes 5 minutes.

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.