Use cat6 in the server rooms for your firewall - router; CISCO is a must for your firewall so PIX 506 and above. use cat 5e for your network, 30 pc's not too match of a hassle! whats with the 5 DC's? thats weired are you runnin a WAN? what do you need all that power for a 30 PC network? and if your are runnin on a WAN you might want to check and make sure you've got synchronization(e.g. outlook, my docs etc) properly configured, also a group policy to block torrent client ports is also a good idea! check your network logger as well!(hey company resources are for official business!! ) hope this helps! later