"If the current rates are sustained, Apple's market capitalization will pass Microsoft's in a couple of years."
That's a big "if", and a big "couple".
Doesn't the Mac have single digit market right now?
Currently, for desktop PCs, their market share is probably in single digits. For laptops, they may have a higher market share. For media devices like the iPod, Apple has a very high share. But market share doesn't tell the whole story. The 'installed base' share for Apple is higher than their market share because Macs typically have a longer lifespan than PCs and aren't replaced as frequently.
I think Apple will gain some share in the traditional desktop market. The new iMac is close to perfection as a desktop computer.
In the future, home PCs will be moving to the living room, attached to HDTV sets. Apple is well-positioned for growth that market.