Any suggestions for network security

Hello everyone,

I am looking for ideas on how to lock down our internet network. At the moment all our staff and parents connect their personal wireless (and sometimes wired) devices to own single internal network to browse the internet and stream media.

I was thinking if there was an application that would look at the hostnames on the Windows Domain and any static IP's that we have reserved in DHCP and place any "other" devices on a VLAN.

I sure this is "pie in the sky" but what do you do for network security?

Kevin