Thanks for the reply. Here are more details on the issue:
I have two users who both use Mac workstations. The external hard drive was attached to the Mac workstations and was fully functional - it was working correctly. The issue was that only one of the users could access the drive at a time.
My intention is to attach the drive to the server and to share it out so both users can access it. I plug the HD into the server via USB, and I can see it under System Profiler>USB but cannot see it in Disk Utility, and it doesn't auto mount to the desktop. The same thing happens when I use a firewire cable.
So again, fully functional when attached to the Mac workstations; when attached to the server it doesn't auto mount or show in Disk Utility, but shows in System Profiler. The drive is powered on, has power lights, works on other machines. It seems like the issue is with the Server... but the only logical explanation is faulty ports. I just dont see both the USB AND the firewire all going at the same time on a server that is only about a year or two old.