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Install python (http://www.python.org/getit/)
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Install pyqt (http://www.riverbankcomputing.com/software/pyqt/download)
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Run 'start.py'
You've probably downloaded a 32-bit copy of python and a 64-bit copy of pyqt.
You need both to be the same; 32-bit or 64-bit, not a mix.