I use mine for
Ha ha! I said "no one", not "nobody". Your math joke reminded me of the Hitchhikers Guide to the Galaxy, in which the answer to Life, the Universe, and Everything is 42.
I use Windows 7 as a developer with .NET, but still use Windows XP Mode in Windows 7 to support legacy applications, our products, and various development tools such as Studio 6.0 projects. I have a rather expensive scanner that does not work with Windows 7, but works fine in Windows XP Mode on Windows 7. My primary complaint about Windows XP Mode, and Windows Virtual Machine on Windows 7, is the inability to map drive letters to specific folders on the host machine. Windows XP Mode allows me to share entire drives on the host machine, which forces me to drill down to the desired folder each time. On the other hand, Windows Virtual Machine on Windows 7 allows me to connect external USB drives and devices. Without the ability to use external USB devices I would not be able to use the scanner with Windows XP Mode O/S. Aero on Windows 7 is really neat.... for about a week. I suppose I could spend days on end personalizing my desktop "experience". But, I write documentation for our products, which require screen shots of the product in action. Some older screenshots were taken on Windows XP with "Windows Classic" UI. Fortunately, Windows 7 allows me to use "Windows Classic" UI so I don't have to retake all of my screen shots again. I use Windows XP SP-3 (via XP Mode on Windows 7) and Windows 7 almost equally, but for different purposes.
No one tells jokes in base-16 anymore. ;)