Static IP's.

In the router setup there is usually a place that will show the connected components, pcs, printers, switches, etc...
In there there should be a place to put in an IP reservation. It will ask for the MAC address which you can get from the list of connections.

I've tried this IP reservation before, and it does work. IF you never change the network devices. I had my file/print server set this way for quite a while, until I upgraded it and it just refused to give the new mac address the IP after I changed it, so I just set it in the server. It's best to just set a specific IP to the device that is out of the DHCP range.

A couple of questions, why do you want to make all the computers static?
What OS is all this stuff running? You do it different ways on different OS's.