TechNet Evaluation Center
With the use of virtual machines taking over production environments, testing the server operating systems combined with the enterprise applications that run across these platforms is crucial for success. All Microsoft software is digitally available online for free. The software is fully functional anywhere between 30 and 180 days.
My Personal PC
One of many ways I practice DR for myself and customers is not activating my Windows OS. Every 30 day I will wipe out my C-drive and reinstall Windows 8 (previously Windows Vista & 7). Sometimes if I'm feeling lazy, I will 'rearm' the license on the last day to give me 14 more days before activation is required. You can 'rearm' the Windows license only 2 times, the command is (run Cmd Prompt as Administrator): slmgr -rearm