Here’s a full feature breakdown of the — typically Windows 8.1 with Bing (for OEMs) and the Core edition configured for minimal resource usage, or the unofficial Windows 8.1 Embedded Industry Pro for thin clients.
If you want : → Windows 8.1 Core 32-bit + manually remove Metro apps + disable services. windows 8.1 lightest version
If you want : Consider Linux (e.g., Lubuntu) or ReactOS – but that’s outside your request. Here’s a full feature breakdown of the —