My experience with internet-savvy teenagers (the next-door duo) is that nothing will stop them. The 14 year old daughter of the family hacked the Admin password of her mum's computer, loaded some software, and neatly trashed the whole machine.
There are routers that can be "secured", but they aren't called Belkin or Netgear. You're talking significantly more expensive devices, such as my Draytek. Even then, a total reset will allow the enthusiastic teen to reload the logon and password bit (assuming those aren't already secret) while disabling the rest of the security.
The only "fix" is to protect your PC and not allow them near it.