No single manufacturer of any PC hardware has 50% nor 25% either. Where everyone else fights over marketshare within the Windows market, Apple has 100% of the MacOS market. And they've been able to get into the top 5 a number of times, even when compared to Windows PCs.
OS X will be a great imrpovement over the legacy MacOS. However, it has a lot of work ahead of it yet. All major software is available for MacOS, however not OSX native yet. I've been working with Macs full-time for over 5 years. I think Windows XP has the edge over the current version of X as far as usability and user experience though. Apple has done a lot of good things to X since the first public release, but they've been a little behind schedule.
And if anyone thinks that any Japanese electronics giant will ever release an MP3 or music product to rival what we have in the empeg and what Apple has in the iPod, they're seriously delerious. This type of device will turn out to be like the cellular phone. Dominated by European and American brands (or at least running their software) - they're the ones with all the best UI talent. Look at Sony's hand-held, a PALM device. Casio's? Windows. Phones? Nokia, Motorola, Ericsson...
Kenwood has made a move to in-car MP3. They're reselling PhatNoise's Phatbox. And these are the types of deals SONICblue should be looking for (and probably are). The HSX could (should) be marketed under some traditional hifi monikers as well (Rotel, Harmon, Denon, Pioneer, etc...)
Bruno