Hi Customer, and thanks so very much for your patience. I know you have endured much on this issue, so I took some time most of today, just to think about how to attack this issue more efficiently for you.
As a result, what I have come up with is a way to allow your Iomega 2TB Home Media Unit, to finally be accessible and Read & Write capable to all of your iMacs, including the uncooperative iMac G5. Below I have provided a suggested idea of what you could do, in order to get this issue resolve. I must advise you however, it would require some changes, including the removal of some components and the adding on of a new device.
This method I am recommending, only because it worked for me when I could not get any other router to work for me. I am suggesting you turn your existing network into an Airport Extreme (or Express) network. Why you might ask? Because it works!
Not only is the Airport easy to add to your existing network, it is an excellent access point, allowing all your Macs, including the G5, to communicate effectively with both Read & Write permissions (so long as the Iomega is formatted properly as an Mac OS Extended (Journaled)
What's even better, the Airport Extreme can connected with your Iomega, via USB, thereby allowing the Airport Extreme to turn the Iomega into an "Air Disk" or wirelessly networked drive. Trust me when I say, it really works well and is not that difficult to set up.
So review this suggested layout and if you are interested in knowing more about Apple's own Airport Base Station routers, here is the link: http://www.apple.com/wifi
Let me know what you think.