Spend $$ instead of $$$$$$ on a Mac Pro
This is a reprint because it’s well worth considering, and has been a popular choice. See also Cameras, Computers or Taxes.
I’ve long maintained that a Mac Pro is a far better investment than an iMac, and you can get a brand-new Mac Pro at a savings that gets you most of the distance to buying the new 27" Apple Display (or a good way towards my greatly preferred NEC 27" display).
Get this 2.66GHz Mac Pro for $1899. It comes with free FREE SHIPPING and several rebates for other stuff. You might be able to find a similar deal at Amazon. It’s brand-new, and eligible for AppleCare just like any other Mac Pro. See Buying a Mac Pro.
With the money you save, you can afford to soup it up as an MPG Pro Workstation; memory and drives and an SSD matter a whole lot to balanced performance. Have it setup and pre-tested, or see Upgrading Your Mac and do it yourself.
It’s a 5% slower clock speed than the current 2.8GHz model (which costs $600 more), but otherwise it’s every bit as good a machine, and the very same model that 90% of my consulting clients have been delighted with over the last 18 months.