A common bit of criticism that Microsoft often receives is the abandonment of old hardware as newer operating systems are rolled out. While fairly new hardware, a few years back or so, will typically work with the latest Windows releases, aging PCs are left behind. Software can be upgraded again and again, but hardware has much more rigid limits. Microsoft understands this, though, and as such has designed a way for people that don't want to use alternative OS'es to continue to use their aging PCs. Dubbed “Windows Fundamentals for Legacy PCs”, the software is available only to people under the Software Assurance license and is intended to convert old machines into thin clients:

The company first discussed the software last September as one of a series of perks intended to improve the value of Software Assurance, which had been criticized by some customers. Fundamentals for Legacy PCs was originally targeted for release last month.
As with all thin clients, very little is run locally, including security tools and document viewers. Production software is all run on remote servers, and supposedly will give a session that very much resembles Windows XP. There are other perks that come with this, and likely this is another way that Microsoft is using to ease people into distributed computing.