Today's the day: October 17th, the day Microsoft starts rolling out Windows 8.1. And right now, the minute this post first went live, is 7AM ET, the exact minute the OS update will start appearing in the Windows Store as a free download. Don't have a Windows 8 device? You can still install 8.1 on a Win 7 machine; you just won't get the update for free. For folks using Windows 7, you'll pay the same price Microsoft was already charging for Windows 8: $120 for the standard version, and $200 for Windows 8.1 Pro. Additionally, Microsoft will also be selling so-called full-version software, allowing you to install the OS on a machine that isn't already running Windows. At any rate, if you've already got a Windows 8 device in hand, we suggest you hit up the source link below to take advantage of the free download. Or, if you're a weirdo, you can also buy a boxed copy in a retail store. We won't judge. Either way, you're going to want to revisit our epic preview breaking down everything you need to know about the new features and apps that come with 8.1.