To the best of our knowledge, Versions 4.11 and 4.20 are fully compatible with all versions of Windows from XP on.
With one minor exception, WinTD 4.10 is also compatible with Windows Vista and later (7, 8 and 10). The issue is the Help system. Beginning with Vista, Windows does not ship with the "Windows Help" application, which has long been the standard system for displaying Help information under Windows. As a result, you may get an error dialog when you try to use any of the Help menu operations in WinTD. (Version 4.11 and 4.20 use the HTML-based help system that is supported by Vista and later versions of Windows).
Fortunately, Microsoft has now made the Help application available as a download. If you get the error dialog when using Help in WinTD (or any other application), just follow the link to download the Help application from Microsoft's web site. After downloading the application, the WinTD help system should function normally.
Version 4.03 generally works well under Vista, 7, 8 and 10. In addition to the Help issue noted above, there is an issue with the Reports-Printer Setup... feature. Under Vista and later versions of Windows, the "Printer" button does not appear in the Page Setup dialog box, so you cannot change the destination printer from within WinTD. Printed output will always go to the default printer, so you will need to change the default printer using the Windows Control Panel if you need to print to a different printer.
We have not done any extensive testing of older versions of WinTD under operating systems from Vista on. However, the installer used with Version 4.00 and 4.01 doesn't operate properly under the newer versions of the operating system---they add stricter requirements. The software itself will run fine once installed, but can't be installed directly off the CD onto a Vista, 7, 8 or 10 system.