Product Windows 10
System requirements 1GHz processor or faster, 1GB RAM for 32-bit version/2GB RAM for 64-bit version, 16GB storage for 32-bit version/20GB storage for 64-bit version, minimum display resolution of 1024x600, DirectX 9 or later compatible graphics with WDDM 1.0 driver
Price Free for Windows 7/Windows 8.1 users; £99.99 for Windows 10 Home and £199.99 for Windows 10 Pro
Windows 10 is two things: firstly, it's an apology letter to PC users burned by Windows 8's touch-focused design and interface, reintroducing choice parts of Windows 7 to create an operating system that can work as well on a desktop as it can on a tablet.
Secondly, it's a major shift in how Microsoft approaches OS releases. Designed to be an ongoing service rather than a one-off product, Microsoft wants as many people to be installing and updating Windows 10 as possible.
As such, it's being offered as a free upgrade to all Windows 7 and 8.1 users, despite costing everyone else £99.99 for the Home version and £199.99 for the Pro version.
To find out whether Windows 10 is a colossal bargain or Microsoft's second questionable OS in a row, we tested the latest .10240 versions of both core editions: Windows 10 Home on an Acer Extensa 2508 laptop, and Windows 10 Pro on a Samsung 700T 2-in-1 tablet.
Updating to Windows 10 is, thankfully, a painless experience. All we had to do to switch the Extensa 2508 over from Windows 8.1 to Windows 10 Home was plug in a USB stick containing the installer, make a couple of clicks, and wait.
About one hour and 20 minutes - plus a couple of automatic restarts - later, Windows 10 was ready. What's more, all our applications, documents, videos and user accounts were carried over without needing to be manually reinstalled; even our desktop shortcuts were in the same order we'd left them.
That's not to say that absolutely everything will survive. Windows Media Centre isn't supported in Windows 10 and thus won't make the cut, and most games and gadgets from Windows 7 will be lost as well.
We're fine with this, though; it was always difficult to find a use for Windows Media Centre, and the likes of Solitaire and Minesweeper can be reinstalled through the Windows Store if they represent some kind of tragic loss.
Changing operating systems can be a daunting prospect, so it's reassuring and deeply relieving that Windows 10 gets off to a strong start with a straightforward installation process.
Next: User interface and Cortana