
Not many people know but only about 1/2 of Apple's sales go to the US market, if you look at DeLL, HP and others, it's similar...
Apple has pushed harder than anyone to get iTunes Stores in most countries, keep in mind it's not easy since it's more of a "legal" problem than a marketing one. Also remember MS's Zune still hasn't made it to Canada, much less the UK or Asia.
Apple's Mac sales over the last 10 years have gone from about 540,000 units every 90 days to 2,100,000 or about 23,333 every 24 hours. Not bad considering Apple still only sells into the high end of the PC market.
Apple will overtake DeLL in the coming 2-3 years and remain No. 2 for the next 10 or so years, probably won't be No. 1 until 2022 or so.