An on-stage hug at Apple's World Wide Developer Conference between Paul Otellini and Steve Jobs, chief executives for Intel and Apple respectively, sealed a landmark deal that will see Apple computers starting to use Intel chips.

Before June 2006 the first Apple computers are scheduled to swap out their Power PC chips from IBM with Intel processors. By 2007 Apple's full product line will have switched to Intel's x86 chips.

A preview version of the new machines running a 3.6GHz Pentium 4 is set to start shipping to a number of selected premier developers within two weeks.

The computers, running a preview version of OS X 10.4.1, are for development purposes only and have to be returned to Apple by the end of next year.

Apple is changing platforms because IBM's Power chips could not deliver the required computing muscle, Jobs told delegates at the developer event.

"We have some amazing products we want to build for you and we don't know how to build them with the future Power PC roadmap," he said.

Power consumption was the most important reason for the switch, according to Jobs, who explained that the Intel chips offer 366 per cent more performance per watt than the Power PC architecture.

Another consideration was the need for greater clock speeds and faster development. Apple promised last year to build a 3GHz PC, but Jobs admitted that the company failed to deliver on that promise. He also complained that it took IBM too long to create the next-generation G5 processor.

"Intel and Apple are a perfect fit," said Otellini during an appearance in Jobs's keynote presentation. He added that Apple is known for its software and hardware design, while Intel is known for advancing chipsets and processors.

"Our strengths are different but entirely complementary," he explained. "We are most concerned about the relentless advance of Moore's Law, delivering better machines year after year."

The change in architectures means that software has to be rewritten and tested for the new systems running Intel, with the exception of widgets and software written in Java.

Apple has been developing and testing its OS X operating system for both Power and Intel x86. To prove that the software exists and works, Jobs used a Powermac running a 3.6GHz Pentium 4 and 2GB of memory for a demonstration during his keynote.