If you are using Windows 7, Windows 8 or Windows 8.1 you only have a few more days to get your free upgrade to Windows 10. After July 29, 2016, Microsoft starts charging for Windows 10 with prices starting at about $120.
I absolutely recommend you grab Windows 10 if you can. I use it daily and like it a lot. It is speedy, easy to use and works well with Xojo apps (and Xojo itself). If you are using Windows 8 or 8.1, there is really no reason not to upgrade as it is better in every way. If you are really fond of Windows 7, you have a tougher decision as Windows 10 looks a lot different and switching might be a bit of a shock.
However, for Xojo developers (or anyone) running Windows in a virtual machine you can take advantage of this free update and still keep your old OS around, which is useful for testing. Depending on the type of Windows license you have, you might be able to just make a copy of the VM file (assuming you have the space — they can be quite large) and then run the Windows 10 update on the copy. Although, I bet after you start using Windows 10, you’ll probably just end up sticking with it.
Now is also a great time to upgrade to Windows 10 because its first major update (called Windows 10 Anniversary Edition — Microsoft has the strangest names) will start becoming available for Windows 10 users in early August.
And remember, if you only use Windows for testing, Microsoft provides 90-day trials of Windows Enterprise that can be used for evaluation purposes. You can grab Windows 10, 8.1 and 8 from here:
Microsoft also makes available free virtual machines for Windows 10, Windows 8.1 and Windows 7 that you can use for testing: