I use the Mac version of NVivo at home, but needed to send a Windows version to my PhD supervisor. I saved the Mac version file to a memory stick, then opened it on a PC at work. I was then prompted to convert it using the QSR software which I was prompted to download. It was a really simple process. There's a guide here: http://help-nv10.qsrinternational.com/desktop/deep_concepts/work_with_your_projects_on_windows_or_mac.htm