Really? This argument again?
I built an i7-based system for my gaming need, and here were the parts:
Intel i7 920
6 GB Corsair DDR3 1600
ASUS Rampage II Gene motherboard
Lite On DVD+/- RW drive (SATA)
One 640GB HD (SATA)
Radeon 5850
Corsair HX750 PSU
Corsair H50 CPU water cooler
Linksys WMP300N wireless adapter
mATX case
Logitech Illuminated Keyboard
Microsoft Sidewinder X8
Windows 7 Professional
Total system cost? $1545 (I actually got Windows 7 Pro for $40 through the educational discount, but the price I used for the estimation was the $130 OEM cost I've seen around)
The entry-level Mac Pro uses the server-based version of the i7 920, but it's comparable. Here's how I spec'd the Mac Pro using Apple's store:
Xeon 2.66 Ghz
6 GB Ram
640 GB drive (default)
ATI Radeon 4870 (last-gen, 5850 is easily better, but highest-available option)
18x SuperDrive (default)
AirPort Xtreme Wi-Fi card
Standard Apple mouse, keyboard
Cost? $2899
So comparable systems roughly (I'd argue the system I built is better, due to a likely better motherboard with SLI/Crossfire support, and the Radeon 5850), but a ~ $1300 price difference. So you're essentially paying $1300 for the Apple name, case, and labor.
I also checked Dell, and after suffering through their horrendous selection process, I was able to similarly spec a system (except using a 5870 instead of a 5850) for $1799. A couple of hundred more than mine, but still $1100 beneath Apple's price.
Don't get me wrong, I love OS X, and think one of it's best advantages is the close-knit nature Apple maintains between the hardware they develop and OS X. But don't try and say that Apple's prices are the same as others.
please, look more carefully to Mac specs, it uses ECC memory which is 3 times more expensive, here is your 1k difference