"Computer Wars", I forget the author and now long out of print, explains that the companies who survive are the ones who can make the tough decisions that cannibalize sales of older products or services in order to move people to new platforms. A good example is Intel, who changed from making RAM to making processors. Apple, however, takes the prize. They're the first vendor to successfully migrate people from extremely disparate systems:
1) from the Apple II to the Macintosh
2) from System 6 to System 7 (ooh, multitasking)
3) from 680x0 to PowerPC
This is far more than the change from Windows 95 to 98 to ME -- Apple's big changes were vast shifts in direction because they required a very different way of THINKING.
I think Apple will be successful with OSX, but it's still too slow and is quite cumbersome for people with a substantial investment in hardware and software to make an easy shift. My graphic designer clients hate it, and Apple should realize that they cannot afford to lose their old client base to $500 gigahertz PC's that have perfectly acceptable performance in Photoshop, Dreamweaver, and InDesign.
I've used a Mac for 18 years now. My primary computer runs WinXP for a number of business-related reasons (including the fact that PC jobs pay a lot better than Mac jobs), but I sprung for a dual-processor G4 this January to handle the chores of my home music studio. I'm not 100% happy with OSX, but I've been asking for these features since the early 90's -- an OS that runs multiple processors, multitasks properly, is terribly stable and has much better memory support than MacOS9. I just hope that Apple didn't miss their window of opportunity by coming out with OSX so late. I mean, some of these features have been around in a nice GUI since <gasp> Windows NT 4 / sp3 in 1997. I should know -- I've used them all.