.... you can turn DHCP off on the router, and set static IPs on the clients, but DHCP is always better.
Bert, from a security perspective, the opposite is true.
When I ran corporate IT, we ALWAYS disabled DHCP, and managed the entire IP space.
We ran a network monitoring script internally that emailed and alerted us as soon as a device started broadcasting for DHCP - it was a dead giveaway that an unauthorized device had been inserted into the network.
From looking at which switch seeing the traffic, we knew which floor/suite the intruder was located, and I always dispatched my 6'5" systems admin to hunt down the intruder.
He would enter conference rooms like a tornado. If I happened to be on the same floor when I got the alert, I'd swing by just to watch him in action. Priceless.