The dual platform clients are generally the most productive since employees are able to work on the machine that works best for them and they have access to both platforms to take advantage of the strengths of each. The Windows-based clients are often surprised when I first bring in my Mac, then amazed at how easily it integrates with their network and helps me to solve their problems. Many companies have successful dual platform networks and the key to their success is nothing more than proper training of their IS personnel. I've used both PC and Macintosh on a daily basis for more than a dozen years in industries including engineering, graphic arts, financial, advertising, medical, and many others. Each platform has its strengths and I would be much less productive without access to both.
Computers are a tool.
A school system with a single platform strategy is shortchanging their students. A few years ago they decided to stop buying Macs and concentrate all future purchases on Windows machines. Missing out on Digital Video and graphic design, areas that are VERY important to the industry and workplace because of a platform standardization would definitely not be in the students' best interests. Also, all of the student access areas for the Mac are always full of people using e-mail and word processing. As both the students and professors feel that the GUI is friendlier, it is preferred for such everyday tasks.