Microsoft has made a major revamp on the Calculator program that comes with Windows 7.
The Microsoft Windows Calculator can perform all of the functions of most four-function (standard) or scientific calculators, and that’s all about it in term of features.
Beside that it has only a simplified user interface, and the core feature set has largely remained unchanged in form and function since Windows 95.
All you have to do is, unpack the content to another folder, and run the calc.exe to use the Windows 7 Calculator in Windows Vista.
To replace existing default Calculator program in Windows Vista, copy calc.exe to \Windows\System32\, and calc.exe.mui (in en-US folder) to \Windows\System32\en-US\ folder, overwriting existing file.
Your Done! Now the new Windows 7 Calculator has been installed on Windows Vista.