>I had started a post with links to reviews and benchmarks, plus a little speculation on why the Apple offering seems to be cheaper than a Dell, but somehow I realized I had a life to live.
To the rescue: Mike at HD for Indies has posted an excellent roundup of what seems to be the fastest/cheapest Windows/OS X workstation, the Mac Pro.
HD For Indies
Update: Here’s a spec list of similarly configured systems with a pricetag at the bottom. Still, the Apple one comes out on top pricewise, giving you a “free” 20″ LCD for the same price as the Dell.