Sam,
Looking at your posts here and on Stack Exchange, I think you have some muddled environment settings.
You want to put C:\Python26\ArcGIS10.0 in your system PATH variable, that gets you to the correct executables from IDLE, PythonWin or the command line.
Your PYTHONPATH could be empty. Or, you could just include the 3 stanzas of your Desktop10.pth file: C:\Program Files (x86)\ArcGIS\Desktop10.0\bin C:\Program Files; (x86)\ArcGIS\Desktop10.0\arcpy; C:\Program Files (x86)\ArcGIS\Desktop10.0\ArcToolbox\Scripts--those paths will then take precedence over the the default search for modules (below the python.exe or pythonw.exe being called).
Finally, since you've uninstalled and installed several versions of Python. At this point, there should be nothing under the C:\Python26 folder except the ArcGIS10.0 folder of the ESRI provided Python 2.6.5 32-bit install. If there is a Lib file there it is a residual of an earlier install and will interfere. It would be a bigger problem if any or your prior Python26 installs were 64-bit.
Also, since you're on 64-bit Windows 7, the Registry path the to 32-bit Python keys are HKLM\SOFTWARE\Wow6432Node\Python If you have a HKLM\SOFTWARE\Python, they would be Keys for a 64-bit install. They also would interfere with the 32-bit install.
Stuart