Microsoft may have more than 90% market share in the operating system business, but Apple is winning the pre-order battle, at least on Amazon. As noted by PCAdvisor, Mac OS X 10.6 (Snow Leopard)and Mac OS X 10.6 Family Pack occupy the #1 and #2 slot in the Bestsellers list for Software, while Windows 7 Home Premium Upgrade is all the way down in the #16 slot.
Microsoft can take solace, however, from Microsoft Office Home and Student 2007 (for Windows) being #3.
Both operating systems go on sale in the Fall (Snow Leopard in September and Windows 7 in October), but Snow Leopard is an upgrade to Leopard, and is priced at $29. Windows 7 will be a full version upgrade, with the upgrade box in the #16 slot priced at $119.99 at Amazon.
No one should walk away from this little anecdote thinking that Apple is going to somehow gobble up more market share than Microsoft -- this is just one online reseller that has always sold a lot of Apple's hardware and software. Microsoft is still the dominant player in the operating system business (at least in terms of sales), and Windows 7 will eventually outsell Snow Leopard, even should it turn out to be a flop.
What this might indicate for real, however, is the idea that Mac users are more excited about Snow Leopard than Windows users are about Windows 7. Of course, even there, the different price tags between the two products makes even that sort of comparison perilous, at best.