It is going to be a long goodbye. Not many people work out two years’ notice, but Bill Gates is a bit of a special case.

His planned departure in July 2008 also leaves plenty of time for speculation on the effect it will have on Microsoft.

In truth, there is little that will happen before or after Gates leaves that would be significantly different from if he was staying.

Regardless of what anybody might think about him or Microsoft’s business practices, there is no doubt that Gates will be remembered as having the single biggest personal influence on technology, and particularly software, during the first 50 years of the IT industry.

Today, his critics try to portray him as a man stuck in a PC-dominated past, unwilling to accept that online software and services are the future. Don’t believe a word of it. If any of us can see how the internet is changing the software industry, it is entirely lacking in credibility to suggest that Gates cannot.

His successor as Microsoft’s chief software architect, Lotus Notes creator Ray Ozzie, is seen as more Web 2.0-aware and as the internet guru who will see through the transitional period to online software.

Come on – has Gates suddenly become an idiot? The last thing he wants is to leave Microsoft being seen as the last vestige of a fading past. He will want his legacy to be leaving the firm in better shape than ever to counter the threat of Google, Yahoo, eBay and all the other web rivals.

In effect, Gates has set himself a two-year deadline to ensure the success of Windows Vista, and to beat Google.

Vista has been something of an embarrassment, constantly delayed and with functionality being dropped. It is likely to be big and unwieldy in programming terms, out of step with the modern mantra of simplicity and rapid development. But it will also be the foundation of Microsoft for the next five years, and will make lots of money.

When Computing interviewed Gates last year, it was clear he was increasingly irritated by questions about Google. He sees it as a fine and challenging rival, but there are no questions in his mind that anything Google can do, Microsoft can do too.

But Redmond today is a juggernaut, impossible to change direction as quickly as it once did, and more considered than in its youth. Do not underestimate what Microsoft is capable of, and do not believe for a moment that Gates will want to leave his company in anything other than the best possible shape for a changing future.