I was a bit glib I guess.
I work in the Oil business in the UK and its dry as toast, I manage the UNIX exploration systems and I see MicroSoft everywhere because its got a huge amount of support from business, its programmers and vendors. Corporate business applications which used to be the perview of UNIX are now handled by some version of MicroSoft. As a side result, I'm a single UNIX person in a sea on PC bods, which are in fact doing less but perceived as doing more by the CEOs that count.
Prior to MacOSX there wasn't a valid OS (I use that in the nicest possible way) on which Apple could compete. Apple, in the areas I'm talking about, has lost out to Linux because the process got started much sooner, i.e. as far back as 1994 if not further.
Example: Another way of looking at it is that geoscientific software vendors, and others like them, will not produce versions of their software on a PPC platform, Apple is still viewed, worngly!, as an OS9 machine with people doing Arty type DTP things. I get that last comment all the time here!
MacOSX has been great!, its been stable, has a good development environment for creating scientific apps (DNA, protein sequencing, molecular dymanmic, etc), Oracle, processing power using clusters. The examples highlight that a MacOSX Desktop machine is a serious beast worthy of attention by companies like Haliburton, Geoquest and so forth.
With the 64 bit G5 chip you gota have a 64 bit OS hence Tiger and just keep the message out there that the MacOSX platform can do everything that MicroSoft, SUN, IBM, HP, SGI, Linux can and a whole lot more given the strength of its desktop applications.
So yes, a 64 bit OS is crucial for survival.
Trouble is MicroSoft's penetration in the corporate sector,into schools and into homes as a result (in the UK anyway), just by simple diffusion alone is 100s of times faster than any active competitor, never mind any advertising that MicroSoft might get up to.