Window Security Grills Burglar Bars
Decorative Window Bars - the next step. Just be sure they have a quick release, or you'll have to remove them when you sell. Fire code and all. :)
GLASSESSENTIAL® Folding Window Grilles are designed to provide elegant look, strong security barrier with ease of operation.
US $24.99 New in Home & Garden, Window Treatments & Hardware, Window Film
Decorative Window Bar Security - Example 1
Window Security Bar - HIDE rebar inside* Found this awesome Product at qcidirect.com
Much nicer than security bars - a strip of dedorative steel lattice in a frame - via Hindsvik Blog
Lexan-ClearBars - Transparent Burglar Bars
Check out this affordable home security idea to protect your windows from break in.
SECURE doors & windows - http://www.hardenedstructures.com/residential-doors.php