Over One Billion Served
Apparently, over 1 billion personal computers have been sold since the the first widely available model, the Altair, came on the market in 1975. Like most other growth models that follow a somewhat exponential curve, that number is expected to double by 2008.
The BBC article has some other interesting facts as well, such as "nearly half of all the households in western Europe have a PC." Yeah, but do they have c3 Custom PCs? :)