Mac OS X is a good thing, but as with all good things, it does come with a price. You must have a modern Mac to be able to use it. Apple states that you must have a Power Mac G3, Power Mac G4, Power Mac G4 Cube, iMac, eMac, PowerBook G3, PowerBook G4, or an iBook to be able to run it. You also must have at least 128MB of RAM to run it (you might be able to get away with less if you don't use any Classic applications).
Apple does not support Mac OS X running on early hardware, although you might be able to get it to run on an older machine. You might also be able to get Mac OS X to run on a machine that has an upgrade card installed in it; however, support for specific upgrade cards is a hit-or-miss proposition.
However, the more costly "cost"?at least for those who have used previous versions of the Mac OS?is that Mac OS X requires that you learn its "ways," which are quite different from previous versions of the OS. In almost every area, Mac OS X is at least slightly different (in many cases, radically different) from previous versions of the OS. It will take some time to get comfortable with how this new OS works (thinking of it as a new OS rather than an update might help you make the jump more easily). And many of the things that were standard practice under previous versions are no longer applicable.
This book will help you make the switch as easily as possible. And when you do, you will be glad you did?the gain associated with learning Mac OS X is definitely worth any pain you might feel. By moving through the rest of this book, you will quickly become quite comfortable with all aspects of Mac OS X.