Microsoft is currently experimenting with a free version of Windows 8.1 that could boost the number of people using the operating system. Sources familiar with Microsoft’s plans have revealed to The Verge that the company is building Windows 8.1 with Bing, a version that will bundle key Microsoft apps and services. We’re told that Microsoft is aiming to position Windows 8.1 with Bing as a free or low-cost upgrade for Windows 7 users. It’s not clear how committed Microsoft is to these plans, but the experiment is part of a number of initiatives designed to push and monetize Microsoft’s cloud services and apps.