I feel this imac is not as fast as the MP, I constantly hear the hard drive working and see beach balls. I have until tomorrow to return it.
You see the beach balls because Mac OS X's Mach kernel sucks. A Mac Pro won't help you there. (Been there, done that, same experience.)
I have a 27" iMac i5 with 8 GB RAM and do not notice any extensive hard disk operations, not even when I launch a Windows 7 VM.
Of course, a current Mac Pro SHOULD be faster than a current 27" iMac -- per definition, the Mac Pro is a workstation class computer and optimized for LOUD performance. The iMac is a optimized for QUIET desktop work.
If you have the budget and if you are resistant to higher noise levels, then the Mac Pro is the machine that you want.
I have only little tolerance to noise in my office/on my desk, and that is why sold my Mac Pro and switched to the quad core iMac: Almost the same performance, but MUCH quieter. For me, that was the best comprise that I could afford.
Your requirements don't sound like you really need that much CPU power, so I think that you do not require a workstation. The iMac should be fine. But since I haven't read to the end of this thread, I don't know if the story already has an ending or not.
