As mentioned earlier, Windows 7 is not dramatically different from Windows Vista. This can be revealed by looking at the version numbers of each operating system. Windows Vista's latest release has the version number 6.0, while Windows 7 has the version number of 6.1. This indicates that, certain new features and changes aside, the underlying code of Windows Vista and Windows 7 are very similar. This is good news if you are migrating from Vista, because it means you'll have virtually no software compatibility issues to worry about. While it is certainly possible that there is a Vista program somewhere in the universe that absolutely won't work on Windows 7, I have never heard of this occurring. If a program runs on Windows Vista, it should run on Windows 7. Windows XP is another story. The version number of Windows XP is 5.1. This indicates that there are some major changes between XP and Windows Vista/7 that run deeper than superficial features and interface work. There is the possibility that the programs you have installed on XP won't work with Windows 7. This is likely if the developer has not released any patches or updates for the program since the release of Windows Vista.