Apple's 10% market share is actually a financial advantage now that application support isn't such a big issue. Whereas it would be hard for Microsoft to grow beyond the overall market for PCs, Apple has plenty of room to grow.
Definitely. They have 10% of the OS market, 10% of the hardware market & good margins on both. Growing from 10 - 15% is admirable, but not as hard as growing from 70% to 105%.
