Download Python 2.7.x from this link (the x86 MSI version) and run it. Make sure to install it for all users and select 'Add python.exe to Path' in the 'Customize' page.
Download and install wxPython, you should choose the 'win32-py27' version.
Now launch 'Command Prompt' from the start menu and enter this command:
sudo python -m pip install rtlsdr_scanner
Now you should be able to run the program:
python -m rtlsdr_scanner
Many new Windows installations are 64 bit, which allows programs to access more memory and is potentially faster. To gain this advantage, follow the instructions above but use 64 bit Python and download the libraries from here.