One of the main reasons we will never be able to be 100% accessibility is that nothing stays the same. The web is a prime example. Companies update operating software, browsers get updated and so do the rules.
To stand a chance of being compliant you have to be constantly updating your site and sifting through what is good for the viewing experience and what is a distraction or unnecessary decoration.
PC or MAC the choice is yours.
Iphone, Android or Bada to mention a few mobile operating systems all offer solutions for accessibility.
Testing on the Mac platforms specifically around the MacBook Pro we have found that the perfect combination for screen reading is the inbuilt mac screen reader and Google Chrome as the browser