what do you do to cover windows from intruders who want to take what you have?
I used glass block for my basement windows. For 2x3 foot openings, I paid $160 per opening, installed, plus $60 for the permit for the whole house.
My first floor windows are all 5+ feet off the ground. I don't worry about them too much, since my doors are a bigger security-risk for now (as they are in most houses). New doors are on the list, both for security and insulation.
My garage windows are Lexan. Lexan is opaque to UV, very impact-resistant (they should stop handgun bullets, which is much better than the walls would do), and while Lexan is not as optically-clear as glass, that's not a bad thing for ground-floor windows. In fact, I'll probably go over them with some steel-wool or sandpaper in the spring to make them a little less transparent.