The last time they took the stage together – in 1997 – Bill Gates was unable to be there in person, opting instead to be video-conferenced in via satellite.

That's why there is, to put it lightly, mild excitement in Silicon Valley at the prospect of tonight's meeting between the Microsoft chairman and Steve Jobs, his arch rival at Apple.

During a 75-minute interview at a technology conference near San Diego tonight, the pair, long considered the grand overlords of the technology industry, will knock heads publicly for the first time in ten years.

There's no shortage of big names at the event, hosted by The Wall Street Journal. Google's chief executive Eric Schmidt, the YouTube founders Chad Hurley and Steve Chen, even Senator John McCain are all dropping by.

But by far the biggest billing is the meeting of Messieurs Jobs and Gates, whose joint appearance will, according to one San Diego-based blogger, create "a disruption in the SoCal space/time continuum".

If you discount the 1997 event, when Mr Gates's satellite appearance at a MacWorld conference in Boston marked a $150 million investment in Apple, the two have not shared a stage since they were photographed for the cover of Fortune magazine in 1991.

There'll be lots to talk about.

Mr Jobs may well compliment his rival on the sale of the millionth Zune media player – a milestone that he may be tempted to compare with the 100 million iPods sold by Apple.

Digital Rights Management (DRM), which has become something of crusade for Mr Jobs, will probably also feature.

Microsoft's Media Player is one of the key planks in the content industry's attempts to protect itself against illegal copying. Mr Jobs has said that he would like to see the technology abolished.

Then there is the past ground – ripe for raking over.

In an interview with The New York Times in 1997, Mr Jobs said: "I wish [Bill Gates] the best, I really do. I just think he and Microsoft are a bit narrow. He'd be a broader guy if he had dropped acid once or gone off to an ashram when he was younger."

A year previously, he had told a PBS documentary: "I have no problem with Microsoft's success. They've earned their success, for the most part. I have a problem with the fact that they just make really third-rate products."

Mr Gates, as if pre-empting the remarks, told Fortune in 1989: "In terms of public relations, yes, Steve is the most successful in the industry. But he does it by saying how crummy everyone else is."

His tone was a little diffferent from 1984, when he said, in a rare gushing moment: "It takes something that's really new and really captures peoples' imagination; and the Macintosh, of all the machines I've ever seen, is the only one that meets that standard."

They could then move on to the reports – perhaps apocryphal – from Silicon Valley folklore that Microsoft placed an 'iPod amnesty bin' on its campus for employees who preferred the Apple device to Microsoft's Zune. Or the fact that Mr Gates has lately stepped beyond technology into global philanthropy while Mr Jobs's company has been mired in an options backdating scandal, or any other of the twists and turns their companies have taken since they were founded in the late seventies.

There to rein them in, should affairs get out of hand, will be Walt Mossberg, The Wall Street Journal's technology columnist, who will be the session's chair.

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