We recently installed a "KVM switch"  (Keyboard Video Mouse) that allows us to use one keyboard, mouse and monitor to control two servers, one with W2000 Server and one with W2003 Server as operating systems.  Is this what you mean?  A 4-port switch was $125.

You can get KVMs that will run up to 8 machines.  some of them will also cascade into each other.  Make sure you get one that works with your server.  Some or PS2 and some are USB.  If you do not have PS2 connections on your server you will want to use USB or buy USB -> PS2 converters.
 
Blackbox, HP, IBM, Lantronix all make one.  Make sure the one you get is Powered or you will have problems starting up your first machine.