ReactOS is a free and open-source operating system for amd64/i686 personal computers intended to be binary-compatible with computer programs and device drivers made for Windows Server 2003 and later versions of Windows., read more on Wikipedia.
If you have old hardware then this is a good idea to use your Windows applications with ReactOS.
The last release comes with version 0.4.14.
I tested the last version of ReactOS with Oracle VM VirtualBox and works very well.
