What is going to be new in Microsoft's Windows 7?

We don't know: it's a secret. However, Microsoft has finally started to talk about its next operating system via a new blog called Engineering Windows 7. This is being written by the top two people on the project, senior vice-presidents Steve Sinofsky and Jon DeVaan.

So far, the plan appears to be to under promise and over deliver - the opposite of what happened with Vista. But Microsoft will soon have to spill the beans. Its huge Professional Developers Conference (PDC) will start on October 27, with the Windows Hardware Engineering Conference (WinHEC) following on.

Microsoft can't keep its plans secret, because its business depends on more than 10,000 PC manufacturers developing hardware to run it and millions of software developers writing and testing their programs. It therefore tends to give PDC and WinHEC attendees code.

In any case, several million people will be beta testing Windows 7, so every aspect will be explored in depth before it's launched. It's not as though it could spring any surprises by selling Windows 7 exclusively on Microsoft hardware from exclusive Microsoft stores.

Still, Windows 7 may feature a SuperBar - a reworking of the old TaskBar - and the "touch" features familiar from the Tablet PC and UMPC (ultramobile) versions will be expanded to include multi-touch as standard. There should also be new versions of Internet Explorer 8 and Windows Media Center, and possibly of Paint and WordPad.

But as with Vista, Microsoft will probably make many new features available to user of earlier operating systems, perhaps even before the launch.

Otherwise, it's not in Microsoft's interests to change much: its main buyers are extremely conservative. They want to run millions of old programs, no matter how poorly designed and badly written. Ultimately it boils down to how much ground Microsoft is willing to give up, if any: it can always make Windows more compatible by making it worse.

But ideally, Microsoft will draw a line in the sand with the 64bit versions of Windows, which started with Windows 2000. It seems 64bit Vista is now making rapid progress thanks to the availability of cheap RAM. While 32bit XP is limited to using a little over 3GB of memory, 64bit Vista machines typically use between 4GB and 8GB or more. The Window Server market has already moved to 64bit versions, for access to large banks of memory, and desktop users will eventually follow.

Then backwards compatibility is solved in a different way. You have a multi-core processor, so just give that bad application its own virtual environment, where it can't hurt anything else. Virtualisation is the future, and Microsoft has the technology. But will enough of it be included in Windows 7?