You have to add the necessary paths to the windows PATH variable. To do this

  1. Right click on My Computer
  2. Click Properties
  3. Select the Advanced tab
  4. Click Environment Variables
  5. Double lick on path

The path variable should contain atleast:

C:\Python25;C:\Python25\Scripts;C:\MinGW\bin;C:\Qt\4.2.2\bin

You may have to adjust the se paths to suit your installationa locations of python and mingw (mingw is installed during the installation of Qt).