Obviously window-mounted air conditioners would help.
Use heavy shades to prevent sunlight from shining into the upstairs.
Use awnings for even more protection.
If the windows you installed are double-paned and are Low E glass, that helps.
An attic fan will suck hot air out of the attic and the whole house, cooling the house faster.
Open the windows at night and use fans to thoroughly cool the space overnight so it starts from a cool temperature.