Upgrade type: Custom
While there were once valid reasons for skipping 64-bit versions of Windows, those reasons have disappeared over the past year or so. As a result, it should come as no surprise that many Windows users are now interested in upgrading their 32-bit version of Windows XP or Vista to a 64-bit version of Windows 7. And because all retail versions of Windows 7 Upgrade come with both 32-bit and 64-bit Setup discs, it would seem that doing so is both supported and straightforward.
Well, it's neither: Microsoft does not support a traditional, in-place upgrade of any 32-bit version of Windows to any 64-bit version of Windows. (Well, I guess that statement is technically straightforward. So maybe they're 1 for 2.)
Here's what you'll see if you try to use your Upgrade version of Windows 7 Setup media to go from a 32-bit version of Windows Vista/XP to a 64-bit version of Windows 7.
But don't despair. If you are the owner of a valid, activated copy of Windows XP or Vista (32-bit), you can still migrate to a 64-bit version of Windows 7. As with other Windows migrations, this process involves four steps:
1. Backup your valuable data, settings, and other information. You can use the Windows Easy Transfer utility, included on the Windows 7 Setup disc, to accomplish this.
2. Boot the PC with the 64-bit Windows 7 Upgrade media and perform a "Custom" install type, wiping out your old Windows install in the process and replacing it with a new Windows 7 install.
3. Reapply your data, settings, and other information to the new Windows 7 install by using the Windows Easy Transfer utility, which is included with Windows 7.
4. Manually reinstall all of the applications you were previously using.
The big difference between this type of migration and the one we discussed in Scenario 1 (Upgrade from a Higher-End Vista/XP Version to a Lower-End Windows 7 Version) is that, this time, you'll launch Setup by booting the PC with the Windows 7 Upgrade media. In the previous scenario, we started Setup from within the previous OS.
Triggering Setup this way changes a few things. When you reach the "Where do you want to install Windows?" phase, where you choose between Upgrade and Custom, you will still need to choose Custom. But, unlike with Scenario 1, you get the advanced options (delete, format, and so on) in the disk partitioning phase. What you choose here is important. If you simply choose the system disk (e.g. the disk on which your previous OS is currently installed), you'll get the familiar warning message noting that Setup will backup your old install in the Windows.old folder structure. However, if you wipe out the disk by formatting and/or deleting it, no Windows.old folder structure will be created. And there are worries that Windows 7 won't activate if you do wipe out the old install.
Fortunately, I've tried it both ways. And both ways have worked for me. That is, Windows 7 activates in both cases, which is what you're looking for. However, I recommend not wiping out the previous install by formatting or deleting the partition with the current Windows version. Instead, simply choose the existing partition and let Setup create windows.old. Once Windows 7 is up, running, and activated, you can choose to delete windows.old to regain the disk space (which could be many, many gigabytes.) It's better to be safe than sorry. (Imagine how awful it would be if you wiped out the old install and then Windows 7 wouldn't activate. Well. I actually do have two workarounds for that too. See Methods 2 and 3 in this article.)