I do not want to sound like a difficult person, but Moodle is not built to work with Windows. We struggled for at least four, and maybe five, years to get it *out* of Windows. It really is a bad idea to leave Moodle's native environment and go to Windows. I can't even list all the trouble we had.
That aside, you just need to make a server for the previous versions and maintain it for the appropriate length of time.
Easier to stay with a Linux server than to go through the pain I'm imagining you are going through. Or, anticipating going through.
If you've got the server, why would you want to leave it?