I ordered 200 Dell Optiplex workstations for a company I was Sys Admin for.
Sent 4 of them back.
I currently have about 90 HP/Compaq workstations and 1500 Macbooks. Servers are a mix of HP, Dell, and XServ.
Apples don't have a magic bullet against hardware failure and aren't any better than any other manufacturer.
What I hate worse than DOAs is inconsistent hardware. I've gotten orders with different video cards, network adapters and even motherboards within the same shipment for the same exact hardware ordered. They were all within spec of the ordered hardware, so they could ship it. We built an image off of one and it started failing on random machines when pushed out. Yep, driver problems. Kind of makes it hard to do a standard image.
Meanwhile, OS X knows all of its hardware, and the enterprise utilities will make valid images specificially for those machines, correct drivers and all.