Whats the best program for sending limited keystrokes?

[Nitro]

I would like to attempt 5 boxing in WoW. I'm looking for a program that will send whatever keystrokes I choose to the other PC's (I have 5+ computers)

Example: When I press any of the number keys 1-9 send that keypress to the other 4 PC's but not any other keypresses, arrow keys, WASD, etc.

[Nitro]

nm, i see multibox does this.

[Runiat]

I believe MultiBox lets you choose what keys to broadcast and what not to. Or maybe it was Synergy. My firewall didn't allow any of them to work and my memory is.. well.. lets just say that I can't remember which word best describes it.