Dolby Atmos claims that it can be decoded in Windows, under certain conditions:
The player must support Media Foundation. Only Windows Media Player/WMP currently does, as a standalone player.
The Edge browser.
Some apps from the Windows App store, such as Netflix.
It's limited to DD+(Dolby Digital Plus/E-AC3) that contains Atmos data.
How to output the result via analog to speakers is unclear, since no sound card output channels for Atmos.
For headphones, an app exists, DAfH (Dolby Atmos for Headphones), which in conjunction with the supported players mentioned above is supposed to virtualize the Atmos information correctly.
In testing the results have been inconclusive, the vertical audio information does not stand out, and generally the Atmos tracks are not distinguishable from the non Atmos tracks.