> I really doubt too many people who are in the market for an HP or Dell workstation are going to consider a Mac Pro

Especially with the gap in Mac Pro releases over the past few years, I have seen many people deciding between Mac Pro and a custom built hackintosh. For the stuff that really justifies a Mac Pro, these were the only two options for some time (short of moving off of an OSX stack). Sure, someone custom building a multi thousand dollar work station is not your typical consumer, but neither is your typical buyer of a spec'd out Mac Pro.