kvm switch

my quest for a kvm: I have just seen one that incorporated the mouse and keyboard signals into the vga cable/socket on the switch itself. At the computer end there are seperate plugs for each, but only one cable that runs to the switch.
This may be a factor in my not being able to get them to work with my computers as I am not using the monitor cables: my lcd has a dvi input and a vga input. I have cables from both computers (one XP and one Mepis) connected to my lcd; I use the menu on the lcd to switch.
So all I really need is a switch that switches just the mouse and the keyboard.
BTW all the kvm switches that I have seen have only vga sockets, I suppose that dvi are available at a price.
If anyone can give me any information I would appreciate it
Thanks