VirtualBox requires very little configuration. You just need a proper disk (or disk image) with Windows, old Mac Os, Linux, DOS etc and you’re ready to go. I wish it had the ability to run mobile operating systems, game consoles and old arcade games!
With 16GB of RAM (XP can only use around 3.5GB due to 32 bit architecture) and Quad-core processor on-board installation of Windows XP was finally a truly exciting experience. :) Also booting-up takes around 3.5 seconds!
It is a great, free tool for testing your website’s backward compatibility with old platforms and browsers.