While Windows 10 isn’t scheduled for an official release until later this fall, you can upgrade from Windows 8.1 to the Windows 10 Preview right now. That means you can test out features such as Cortana on the desktop, the Xbox app, the new Start menu, and the Action Center for yourself.
There are many ways to install Windows 10 on your PC, including doing a clean install, using a virtual machine or putting it on a separate partition so you can dual boot it. If you have Windows 7 (Service Pack 1 or later) or 8.1, however, you can do an in-place install which writes over your existing operating system but saves your preferences and installed apps. Here’s how to upgrade directly from Windows 7 or 8 to Windows 10.
Before you begin, we recommend backing up your entire system, just in case something goes wrong or you want to uninstall Windows 10 and go back to Windows 8/8.1.
1. Navigate to the Windows Insider home page and sign in
If you are not an insider, sign up for free.
2. Click Continue at the bottom of the page.
3. Click “Get the Preview” at the bottom of the page.
4. Click “Start upgrade now.”
Your browser will download a small executable to get the installation started. Save the file somewhere you can easily find it again (like the desktop).
5. Open the Windows10TechnicalPreview.exe file you just downloaded.
6. Click the Restart button
Which appears after you wait a couple of minutes for it to prepare the installation.