iMacs are laptops
Every Mac Pro revision after its introduction in 2006 has raised the prices of the midrange configurations. Mac Pros are now so expensive that almost nobody like me — geeks who like big, fast, expandable desktops but don’t do many long-running CPU-bound tasks, like video processing, for a living — can afford or justify them. Sure, I’ve gotten three solid years of use (so far) out of this one and it’s still doing fine, but it was also only $2800 for the mid-speed dual-socket model. (The similarly positioned model in today’s lineup is $5000 and is approximately 2.5 times as fast, which, while impressive, isn’t as far ahead as I’d like it to be for that price.)
This pretty much sums up why I gave up on the Mac. I was no longer interested in having a huge 24" laptop. I was tired of having 4 external drives besides the iMac. The overall noise level around my desk has decreased by not having all those drives (amongst which was a Drobo with a rattling fan) there.
And the Mac Pro is just unjustifiably expensive. I'm now running on a home-built desktop, Sandy Bridge i7, lotsa RAM, and an SSD. Ubuntu, with a Windows partition for Lightroom and Photoshop (okay, and games). I hope one day Adobe will release their software for Linux too, but I can boot Windows from within Linux, and I can boot Linux from within Windows, so all in all it doesn't really matter too much which operating system I happen to have booted up natively.