Two of the hottest tech gadgets are mobile phones and GPS units for your car. Both can simplify your life enormously or, if you're not careful, ruin it. To protect yours: Never program your home address into your GPS. If your car is stolen, all the thief has to do is hit that Go Home button to be guided to your place and, since he knows you're not there, press the garage-door opener for access. Instead, program a local store's address. Be careful how you list people in your phone's contacts list. If you lose your cell, the thief can text Hubby for a 'forgotten' PIN and then use your bank card to clear out your account. Use first names instead.