Just as Microsoft is about to abandon its DOS-based Windows 95/98/ME operating systems in favor of Windows XP, Apple's Macintosh OS is about to undergo the same divergence. Apple has recently introduced MacOS X (OS Ten) which is an operating system based on Unix. Apple's operating systems 7-9 did not have the features that modern computer users needed to use their computers effectively. Apple developed OS X to address these limitations.
If you were to look at a list of software for the MacOS, you would find most every major product that has a Windows version also has a Macintosh version. Since the Macintosh market is smaller, there tend to be fewer higher education, academic, and business applications. In K-12 education, there is virtual parity between the two computing platforms.
Upgrading to MacOS X will not be as seamless as upgrading from Mac OS 7 to 8 to 9. MacOS X programs and drivers (small programs that tell the computer how to communicate with other pieces of hardware) have to be rewritten for the new operating system.