I guess I should explain my situation here:

I have a box running RedHat 6.1, this machine sees all the traffic before passing it on to the wireless router.

My question is this, is it possible to make it so none of the above programs will function on any of the networked computers, and if so how... I have some idea but I don't want to mess around in there when I don't know what I am doing.

Someone might very well come along and have a better solution, but I would think you could use iptables to stop all network traffic on the default ports that each of those three networks run on. You can't actually prevent the programs from being run on each individual computer, but that should essentially make them useless unless they are set to operate on a different port than the normal one. I can't provide specifics on how to configure iptables since I've never used it, but I'm sure either someone else here could tell you or there is a guide that would give you the general statements to use.

Your Redhat box sees all traffic - does your rh box have 1 network card that is plugged into a hub (not switch), or does it have 2 network cards, with the wireless router on 1 side and the network on the other?

It will be difficult to control traffic if you have the first scenario, but if you have the 2nd, you could use SSTwinrova's suggestion and use iptables.

kazaa uses port 1214, so you could use a FORWARD DENY rule for tcp port 1214. (or block all forwarding by default and only allow forwarding of what you need).

Another alternative is to disable forwarding and to configure a proxy server (such as squid), and then use the access control features of squid to restrict what the local network can and cant do.

It is the second scenario you described, and I am going to give the iptables stuff a shot!

great