lol understandable more than ya lifes worth to lockout wife n kids!
It will take a bit of configuring but it's not that hard to do, you just setup a password/key which you set in each of the boxes you want to let have access, boxes that don't have the key won't be able to connect!
You'll need to have a read of the manual for ya router that should point you in the right direction for security settings, once that's setup then setup each box you want to have access.
There are plenty of threads here about wireless security and I'm sure others will help if you run into probs.
As well as using passwords for your wireless network you could also use mac filters. Most routers have these options just read up on your own routers security features. Add the mac addresses of all your network devices onto the list of allowed devices and then no one else will be able to access your network. This is not 100% proof as mac addresses can be spoofed but if someone knows how to do this they could probably hack you password anyway.