He does not contest that he sent the letters to three forensic science laboratories, a computer company, an accountancy firm, the DVLA and a residential address, but denies intending to cause injury.

BBC: NEWS | UK | Bombs sent 'in protest at state'

Richard Bejtlich, chief security officer at Mandiant, a computer-security company, said that in cases handled by his firm where intrusions were traced back to Chinese hackers, 94% of the targeted companies didn't realize they had been breached until someone else told them.

WSJ: U.S. Outgunned in Hacker War

His firm, and others like it, are starting to turn out computer models that can estimate for an insurance company the cost of a storm even before it happens.

ECONOMIST: Eye on the storm | The

But HP, a company synonymous with the birth of Silicon Valley, and Compaq Computer, a Houston-based firm which once pioneered PC price-cutting, may yet have to restructure their deal or abandon it entirely.

ECONOMIST: Doubts about the wedding | The