This tool especially is useful in places where different people (Left-handed and Right-handed people) use same computer frequently, like schools, libraries, etc.
SwapMouse is very simple to use. Download and unzip it. Double click the ‘swap mouse.exe to swap right – left mouse buttons, once again click to revert back it (no GUI to configure the tool).
SwapMouse tested on Windows XP and Windows 7. You can download the freeware tool from here.