“Every executive in the PC industry should use an apple notebook".
That really shows a lot of faith in your product. If I saw someone from using 's product, would I be buying from you?
The answer is simple: NO. If you have no faith in your product, why should I buy it? If your company does not stand behind its products, why should I use them, even if the other company's products do indeed work better?
That notwithstanding, Macs aren't designed or meant to be for executive use, for a couple of reasons:
First, Macs exist to make more of a 'I'm so cool because I spent lots of money on my laptop' statement- not an 'I focus on the hardware and cost and make decisions that way' statement. "I'm so cool" is not important nor appropriate in a business environment.
This is why Macs are found most often in photo studios and other, more art-focused businesses where having a Mac is important (since, arguably, they are better at that end) and cost isn't (also due to the 'cool' factor).
In a boardroom, however, I would make a decision based on who has the best business: if you show that you don't know how to make good decisions, I won't pick you. Looking cool loses in the face of sound buying sense almost every time. Showing me that you don't believe this is so will lose you that decision.
The second point (which ties in with that) is that Macs are substandard computers compared to PCs of the same price point.
Macs are filled with second-rate hardware, cost more than a PC of comparable build quality, and for no logical reason whatsoever other than 'looking cool'- since Windows 7 (or Linux) can do everything OS X can: therefore it is not worth the expense. Couple that with the fact that a Mac is unusable after 2 years because the battery won't hold a charge, and you have the answer- an inferior computer at a higher price.
Experience-led thinking shows you that PCs, especially your company's PCs (or OS or whatever) are the way to go.