First of all: that's the wrong version of Python, Softimage runs with Python 2.6.x or earlier.
Second of all: From the path in your previous post I gather you are using SI2012. From SI2011 upward Python should be installed "automagically" with your Softimage install, you should only have to tell Softimage to "Use Python installed with Softimage" in the Scripting Preferences. (Look here)
Thirdly: If you really want to/must install an "external" (i.e. not installed with Softimage) Python, follow the steps described here, as you will have to install not only Python, but a corresponding version of pywin32 also...
And feel free to ask if anything is still unclear, obviously... ;)
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