Tiny7

Tiny7 is a stripped version of Windows 7 that used to be the sole VM for CollabVM. The older server was actually fully capable of running the full Windows 7, but it wasn't able to run it because nested virtualization is a piece of shit. The end.

Tiny7 is based off of Windows 7 Ultimate RTM 32-Bit, you can't install optional components or anything that uses windows update, and .NET is broken on it.