If your router connection is encrypted then you should have no problem and nothing to worry about. The three types of encryption available are WEP, WPA and WPA2. WPA2 is the strongest, the most commonly used and most routers today will default to it. It will take days at least (weeks if you have selected a powerful WPA key) constantly running intense hacking software to try and break it. Changing the key regularly will enhance your security. You should feel completely secure with just these two practices.