Microsoft unveiled a new look and user experience for MSN this morning — but users won’t actually see it on their screens until and unless they’re running Internet Explorer 10 on Windows 8.

The new MSN uses a modular, tile-based interface reminiscent of Windows 8, designed in part to be easier to use on tablets. It will launch on Oct. 26, coinciding with the debut of the new operating system. However, for the time being, MSN will retain its existing experience on other browsers and older versions of Windows and other operating systems.

Why only on Windows 8 and IE10? A Microsoft representative says via email: “We’re making this available only on Widows 8 machines running IE 10 so that we can showcase all the power of this new platform in support of the company’s launch. By being able to take advantage of technologies in Windows 8 and IE10, we were able to create a new experience that is significantly faster, offers a seamless design that is built for touch, and delivers customers an even wider range of content trusted and real-time sources.”

The company says it isn’t ruling anything out long-term, but the immediate goal is to support the Windows 8 launch.

In a blog post about the new experience, MSN General Manager Bob Visse says the overhauled portal renders pages twice as fast as “the classic MSN experience,” taking advantage of Internet Explorer’s use of the Windows 8 system architecture.