The next billion will be sold in just six years, as high-growth markets emerge in China, Latin America and Eastern Europe, Gartner said.
But with "the wealthy heart of the PC market [the US and Europe] consumed," vendors will have to lower prices to tap developing markets in an industry which is already fiercely price-competitive, the research organisation warned.
In 2000, the industry's best year to date, around 132m PCs were shipped worldwide, and the industry is expecting a similar figure in 2002 as the market recovers from a weak 2001.
Further consolidation of PC vendors is likely as rivals try to match the strength of Dell and Hewlett-Packard. Dell's direct sales model has enabled it to achieve very low level of selling, general and administrative expenses, which other vendors are struggling to match, Gartner said.
The PC industry - which in 2001 saw a decline in sales for the first time since 1985 - will receive a boost when there are widespread broadband communication connections at data rates in excess of 10Mbps to households, according to Gartner.
The personal computer landscape has changed a great deal since the first personal computers were introduced in the early 1970s, Gartner said.
Those claiming the title of the first personal computer - desktop-sized, programmable, affordable and simple to use machines - include the HP 9830, introduced in 1972, with the BASIC programming language in ROM, The 9830 then cost $5,975 (£3,900).
A French machine called the Micral followed in 1973, as did the Xerox Alto, which featured a mouse, a graphical user interface, an object-oriented operating system and development tools, along with fast networking from the first Ethernet cards.
The 1975 MITS Altair 8800 is regarded as the first commercially successful and widely available personal computer, and was also the first PC to run software developed by the fledgling Microsoft. The Altair contained an Intel 8080 chip with a clock speed of 2MHz, while today's high-end Pentium P4 machines have a clock speed of 2.53GHz, more than 1,000 times as fast.
The $1,295 (£850) Apple II (1977) and the $2,880 (£1,900) IBM PC Model 5150 (1981) started the rapid growth of PC sales, but it took the market almost 15 years to cross the 50 million units per year mark and just another four to cross the 100 million per year mark.