'ThinkPad is the standard-bearer for notebook computing, and that's because we listened to our customers from the very beginning,' said Fran O'Sullivan, general manager at IBM's personal computing division.

Since its introduction in 1992, an era that began with the now-ubiquitous 'clamshell' notebook design, ThinkPad has delivered many 'firsts' in the industry, according to IBM. These included being the first notebook with each of the following: colour liquid crystal display (LCD) panel, 14-inch LCD screen, full-sized keyboard and removable hard drive.

'We listen to our customers. Find out what they like and value from a notebook system and then we add what we learn to the next round of products,' Ms O'Sullivan said. 'They get better and better every year, but the basic ThinkPad attributes remain unchanged - innovation, reliability, performance, security, ease of management, ease of use.'

Other milestones achieved by IBM included: first 10.4-inch colour thin film transistor display and TrackPoint pointing device (ThinkPad 700C, 1992), first with integrated CD-ROM drive (ThinkPad 755CD, 1994), first 'ultraportable' model (ThinkPad 560, 1996), first with DVD-ROM drive (ThinkPad 770, 1997), first with integrated wireless local area networking capability (ThinkPad I series, 2000), and first with extended battery life of up to 11 hours (ThinkPad X31, March 2003).

IBM's competitors have already adapted many of the technologies that ThinkPad pioneered.

That situation has led to the fast climb of Dell Computer to the top of global PC sales, outpacing overall demand for IBM machines. The Texas-based firm has competed on lower cost, speedy delivery and direct sales to become the largest seller of desktop and notebook products worldwide, competing mainly against Hewlett-Packard.

Still, IBM continues to push innovation on its ThinkPad. Its 'active protection system', introduced last month, helps protect the notebook's hard drive, and responds much the same way an air bag protects a vehicle's passengers.

'From the first Intel processors to our new Centrino mobile technology, IBM's ThinkPad has been a pioneer in delivering leading-edge computing capabilities,' said Anand Chandrasekher, vice-president and co-general manager at Intel's mobile platforms group. 'The shipment of the 20 millionth IBM ThinkPad, based on Intel mobile technology, represents a milestone in the richness and popularity of the mobile computing experience.'

Aside from receiving more than 1,000 industry awards since its inception, IBM also claims that its ThinkPad notebooks have been used in numerous space shuttle missions and carried during several climbs to K2 and Mount Everest. A ThinkPad notebook is also included in the permanent design collection of The Museum of Modern Art in New York.

Steady demand for ThinkPad systems in Asia are also credited with boosting IBM's worldwide notebook sales. According to second-quarter sales estimates by International Data Corp (IDC), ThinkPad shipments to the mainland reached 11,500 units, while demand from Hong Kong totalled 18,200 units.

A joint venture between IBM and China Great Wall Computer Group, Shenzhen-based International Information Products, was formed in 1994 to make ThinkPad notebooks for Asia and parts of the United States and Europe.

Alfred Cheng, general manager for IBM's PC division China and Hong Kong, said in September that unit shipments of IBM notebook and desktop PCs increased more than five times faster than the Hong Kong PC market in the quarter to June 30 this year.

Figures from IDC's PC Tracker report showed that IBM PC sales in Hong Kong were up 26.5 per cent over the same period last year, while the market as a whole increased only 4.6 per cent.

IDC said notebook sales accounted for 60.5 per cent of Hong Kong PC market revenues in the second quarter. In this market segment, IBM increased its unit sales share from 26.5 per cent to 30.4 per cent year on year, while its revenue share rose from 27.8 per cent to 31.6 per cent year on year.