If you're in the market for a new computer, think laptop over desktop. A laptop computer uses up to one-third less energy than a desktop. Newer laptops feature even bigger environmental savings, including LED-lit screens, which are free of harmful mercury. Look for laptops that are Energy Star certified. And be sure to recycle your old computer whenever you buy a new one. RadioShack will appraise the recycling value of your old PC or Mac and give you a gift card for its value on the spot.