If you've been wondering when Microsoft would finally roll its brand new Project Spartan web browser into a version of Windows 10 you can try, wonder no longer. The Redmond crew has released a preview build of the operating system (10049) that includes Spartan, so you can check out Cortana voice commands, annotation features and speedier rendering for yourself. The software is still rough around the edges and won't have every feature due when Windows 10 ships this summer, but you can give it a shot today if you simply can't wait to kick Internet Explorer to the curb.