The netbook has become a runaway bestseller, and as economic conditions bite, consumers are being drawn to the cheap, compact machine. It's a prospect that could trouble PC builders and chipmakers alike. For the first time since the birth of text messaging on mobile phones, a technology segment has caught the mobile computing industry by surprise and this time, it is taking the PC business along with it. To get an idea of how volatile this new market is, consider that, while it may already account for millions of units in sales, nobody quite knows what to call it. 'Netbook' is the most popular term, favoured by Intel for close to a year, although Psion trademarked the term a decade ago and is now sending letters to manufacturers asking them to stop using it. Consequently, other names have popped up, from the descriptive 'mini-notebooks', 'subnotebooks', 'low-cost, ultra-light devices' and 'laptop lites', all the way through to the whimsical 'liliputers'.