Plain distilled white vinegar does a wonderful job of cleaning windows, unless they have already been washed with commercial glass cleaners. Before you can utilize plain vinegar as the official window cleaner of your environmentally friendly home, you must remove all waxy residues by washing the windows with the following solution:
1/2 cup white vinegar
1/2 tsp. liquid dish soap
2 cups water
Pour the mixture into a spray bottle , spray the solution on your window, wait half a minute, then polish the glass with a clean rag. The dish liquid will break down the wax so the next time your windows need washing, you can spray them with full strength white vinegar, then use a rubber squeegee or a clean, soft rag to dry them.
from Organic Housekeeping by Ellen Sandbeck, p. 269