You might want to do some research at http://smallnetbuilder.com
Check out the NAS charts to compare the speeds of the different units as well. I've setup two QNAP servers and they work great.
You seem to focus on Firewire a lot in your post. A NAS (Network Attached Storage device) is just that... it hooks into your network with Ethernet, not Firewire.
Only you know exactly what you want. You will need to put forth the effort to do the research. Just asking someone to tell you what to get is not a good way to go about it. It tells the person that you don't want to put forth the effort. That person has to research all the options for you. It's not like they can know exactly what you want and pull it out of their hat. It requires research. The Internet is a great place to find out anything you want to know about a Network Attached Storage device.
