Ok, when our lan switched to DHCP, and my linux boxes dropped off the network, it is because the DNS wasn't set correctly. Got the DNS set now, and they are showing up in my Exceed XDMCP broadcast box however, i now have another problem. They access the internet. I don't want them to. HOw can I set them to stay within our internal network only? we have a router, firewall (cisco) but I don't want anyone to be able to access them from outside our internal network.

Your safest bet would probably be to ask the Network Admin to block incoming to your boxes at the border router / firewall. I don't know if you want to block incoming and outgoing, but either way should be a relatively simple excercise for him (or her).

You may want to do that post-haste if you have not properly secured your boxes (and X isn't too terribly secure to have open, let alone floating around...).

Will do! Thanks !

why not just remove your default gateway on your linux box (assuming its setup) in your routing table(s)?