To date, reinstalling Windows has meant using a local copy -- either something already stored on your PC (and thus at risk of going bad) or something external. Soon, though, it might just be a matter of grabbing it online. On top of changing tablet mode, the latest Windows 10 Insider Preview Build on the Fast ring includes a "download Windows" option when you want to reset your PC. Much like the feature Macs have had for years, you can use your broadband connection to grab a fresh install from the cloud. You don't need a backup partition or a thumb drive to get back in business.