The speakers have magnetically shielded components (was used by TV) so that isn't a problem. I wanted the workstation to be portable, so it is on casters. And, I hard mounted the speakers with brackets to the frame, so that I could roll it around and not have to worry about them moving. So far I'm pretty happy with it. What you cant see is the 12-space rack behind the iMac for my amplifier, firewire interface, etc.
Now all I need is some suspended surround sound speakers looped over the top.