I use the same detail spray on the windows as the I do on the outside of the car; Meguiar's Ultimate Quick Detailer.
A quick tip: wipe horizontally on the inside of the glass, and vertically on the outside. That way, if you do have streaks, it is easy to tell which side they are on.
So, the "ultimate quick detailer" does windows well? I'm a little surprised but glad for the information.