Error :No module named qgis

Question

I am working on Python26,pyqt4 designer and QGIS. My code file (.py file)contains this:

   import sys
   from PyQt4 import QtGui, QtCore
   from qgis.core import *
   from qgis.gui import *

but when i try to run it it gives error saying:

Traceback (most recent call last):
  File "C:\rt_sql_layer_working\DlgQueryBuilder.py", line 29, in <module>
    from qgis import core,gui
ImportError: No module named qgis

I already set PATH in environmental variable as

C:\Program Files\Quantum GIS Wroclaw\bin
C:\Program Files\Quantum GIS Wroclaw\apps\qgis\bin