When inspecting the windows, make sure you can actually open them. You face a huge safety hazard if the windows do not open properly. Every room should have at least one window that can open.
Make sure the windows aren't leaky and that the glass isn't chipped or broken. You don't want any missing panes of glass, either. The windows should operate normally and lock from the inside. In addition, they should all have screens and the glass should be clean and free of mold and mildew.
Check the blinds as well. They should work properly and not be broken in any way. Also, make sure they aren't dirty or stained.