Most people who install the Windows Technical Preview will probably upgrade an existing Windows 7 or Windows 8.x-based PC to this prerelease version of Windows 10. The good news is that there are no surprises, and that this process works exactly as it does with Windows 8. Even better, most of my upgrades have been trouble-free.
And yes, I wrote "most" there. It goes without saying, or at least it should, but the Windows Technical Preview is pre-release software and is essentially unsupported. So it's reasonable to expect a base level of technical expertise here, and an understanding both of what you're getting into and what you can do if things go wrong.
That said, here's a quick check-list of common sense things to do or at least consider before upgrading:
Make a recovery disk. This is a called a system repair disc in Windows 7. Here are Microsoft's instructions for creating this. For Windows 8.x, please read Windows 8 Tip: Create Recovery Media.
Make sure you have OS install media. It's possible this is built into your PC, so find out. If not (or regardless), make sure you have physical media that you can use to reinstall your original version of Windows. Or...
Backup your entire system. Use the system image backup feature in Windows 7/8.x to make a complete system image of your PC. Then you can boot it with the recovery media mentioned above and get your PC back to the way it was. Check out Windows 8 Tip: Use Windows 7 System Image Backup and Windows 7 Feature Focus: Backup and Restore for more info.
Backup your data. This can take many forms. I use OneDrive sync for all my data so I don't need to do anything additional. But you may want to at least copy important data to a USB-based flash drive or hard drive, or network location before upgrading. Don't lose anything important.
Ensure you have access to the drivers and applications you need. If you do need to reinstall Windows 7/8.x because everything went south during the Windows Technical Preview, it would be a shame to get your old OS up and running again without networking drivers. Do a bit of due diligence and download the latest drivers for your PC now, just in case. And where possible, keep offline installers for the applications you use the most too.
Deauthorize applications just in case. Some applications—notably Apple iTunes—require you to authorize them for use with your online account and then hold it against an application count. The upgrade should go fine, but just in case, deauthorize these applications first. And if all is well, you can reauthorize them on the other side. (Look at your Adobe applications too.)
So what's it like upgrading?
Honestly, it's pretty simple. Here's a quick step-by-step guide.
After creating the install media as described in Windows Technical Preview Install Guide: The Basics and ensuring that the PC is completely up to date with Windows Updates, you can insert the USB- or DVD-based Setup media and launch Setup. Then....
Accept the license terms.
After Setup examines your system, you have one big choice to make, though this screen assumes you wish to perform an in-place upgrade in which your current OS is upgraded to Windows Technical Preview, retaining all of your desktop applications and apps, and their settings, your OS settings and customizations, and your data.
If that is not what you want, click "Change what to keep." Then, in this screen, you will see the following options:
Keep Windows settings, personal files, and apps. The default, and what is called an in-place upgrade.
Keep personal files. A migration, in which Setup backs up your documents and other data, clean installs Windows, and then returns your documents and other data to their original locations.
(Keep) Nothing. A clean install, in which Setup erases your existing Windows install along with all of your settings, applications and data, and then installs a factory-fresh version of the Windows Technical Preview.
I'm going to assume you're doing an in-place upgrade, however. After you agree that you're ready, Setup goes full screen and continues...
Your PC will then reboot and Setup will perform a variety of actions that will depend on which type of install you chose.
After a few more reboots, the Windows Technical Preview out of box experience (OOBE) begins. This is somewhat truncated because it's an upgrade. First, you choose between Express and Custom settings. These settings have not changed since Windows 8.1 Setup, as this is still in fact using Windows 8.1 Setup, so there's no need to step through all of it. In short, I recommend using Express settings. But you're welcome to go through Custom settings just to see what the defaults are and change some if you feel it's warranted.
Next up is account setup. If you're upgrading from Windows 8.x and were using a Microsoft account for sign-in, you will be prompted to sign-in to that account and move on. If you are upgrading from Windows 7, however, or from Windows 8.x and were using a local account, you will be prompted to sign-in to your Microsoft account.
I continue to be amazed at the weird resistance by some to using a Microsoft account for sign-in, since this provides such a huge advantage with regards to settings sync, OneDrive integration, Windows Store application access, Xbox-based music and gaming subscription services, and more. But rather than get into a debate about that now, I'll simply assume you want to use Microsoft account because that is what most people will indeed want. (If not, click "Create a new account" instead and then "Continue using my existing account" in the next screen.)
After you've signed in with your Microsoft account, you will be told that OneDrive is connected to your PC and will be available through the file system and for settings sync. You do want this. (If not, click "Turn off OneDrive settings (not recommended)." Don't do that.)
Now, you can enjoy a nausea-inducing interminable wait while colors flash on the screen and Setup finishes up. Sorry.
And finally, you will be presented with the Windows Technical Preview. What you see here will depend on which OS you upgraded from. With Windows 7, you will boot right into the desktop and the new Start menu will be enabled, as seen here.
But with Windows 8.x, the Start screen will be enabled by default. (You can switch to the Start menu using the instructions in Windows 10 Tip: Swap Between Start Menu and Start Screen.) And whether you boot to the desktop or the Start screen will depend on how Window was previously configured.
At this point, you should make sure everything works. Here are some ideas I first published with much more detail in Windows 8.1 Field Guide:
Set the date and time. Make sure that your PC's date, time zone are correctly set before doing anything else: The time zone, in particular, is often incorrect and is annoyingly set to Microsoft's home time zone of Pacific Time for some reason.
Install all Windows updates. The Windows Technical Preview is configured to automatically update all important and recommended updates. But while this does happen automatically, it doesn't always happen immediately, and one of the things you will need to do after installing Windows is ensure that all of the latest hardware drivers are installed. On many PCs, this will occur through Windows Update. Seriously, this is crucial. Don't do anything else until you've installed all the available Windows Updates.
Check Device manager for missing hardware drivers. Yes, Device Manager is an old-school desktop-based control panel, but it's also the only accurate way to see whether all of the hardware devices in and attached to your PC are supported by valid drivers. There are a variety of ways in which to display this tool, but the easiest, perhaps, is to navigate to the Start screen, type device man and then select Device Manager from the search results list. If all is well, you will see a "clean" Device Manager with no driver-less devices. If not, you'll need to do some research and downloading and installing.
Personalize Windows. Once all that is done, you should think about personalizing the Start screen and other aspects of Windows. That, of course, is a topic for other articles.
Make sure your applications work and, if necessary, reauthorize them.