Microsoft to biz: Just so you get off XP, we don't mind if you go Win 7

ISVs coming by the week?

Visser conceded that buy-in from ISVs is "very important". However, he claimed the shift to Windows 8 for them is "no different" than upgrading their apps for Windows XP and Windows 7. Back then, you built software that was installed from a CD, DVD or over the network to a hard drive or onto a corporate desktop image.

But Windows 8 is a different story. Windows 8 apps are downloaded from an online store. A UEFI boot security system on the PC motherboard prevents unauthorised code from running. Meanwhile, the interface has undergone a seismic shift, with mouse and keyboard giving way to touch and swipe.

Visser told The Reg Microsoft is working with ISVs to support Windows 8. "Every week you will see business ISVs making announcements around Windows 8," he promised.

What do ISVs need to see to convince them to write apps for Windows 8? Proof of market acceptance - an iPhone or iPad-like tipping point before they'll both re-building and supporting apps for Windows 8? Visser wouldn't be drawn. App-building for Win8 offered devs "the opportunity to build new and innovative apps and leverage their current knowledge," he said.

Until there is that Apple-like tipping point that gets the Oracles and Salesforces on Windows 8, Microsoft will have to rely on the ability of Windows 7 apps to run on Windows 8. But, as you'd expect, the picture isn't that simple.

Windows 7 apps written for x86 won't run on Windows tablets running Windows RT, the version of Windows built for ARM. You can install Windows 7 apps on Window 8 machines running Intel chips without a Microsoft secure key - but should you be able to get a legacy app to actually work on ARM, you'd need a Microsoft key to work with UEFI boot.

Installing Windows 7 apps - what Microsoft is calling Line of Business (LoB) apps - means embarking on a process called sideloading. Again, this being Microsoft and Windows 8, sideloading is not straightforward.

You can sideload on Windows RT, Windows Server 2012, Windows 8 Enterprise or Windows 8 Pro. The snag is: when it comes to the client, machines must be "domain joined". Only Windows 8 Enterprise can be what Microsoft calls "domain joined" - which, in non-Microsoft-speak, means attached via Microsoft's Active Directory.

Without domain joining, you are required to have a Microsoft product activation key, which comes as part of a Microsoft volume licence.

If anything was designed to discourage anybody from putting legacy apps on Windows 8, then it's forcing their entry into the minefield of licensing.

For all this work, Windows 7 apps won't get that signature Metro effect UI - so no tiles, no data and workflow integration, and no swiping.

It's a complicated and an uncertain picture. No wonder Microsoft has made Office 2013 and versions of its Dynamics business apps available for Windows 8. This should help carry people over. No wonder BT and Poste Italiane are finding their way carefully - they are companies which, unlike the rest of us, were members of Microsoft's first wave adopter programme and they have already conducted pilots, meaning they got plenty of support from Microsoft.

Scott revealed two challenges. The first actually goes back to Windows XP, as some of BT's core CRM apps remain tied into Windows XP's browser, IE6, and don't work in the Windows 8 browser, IE10. Scott says his IT supplier has promised to have solved the issue by next February.

The other challenge cuts to the heart of Microsoft's advice to run Windows 8 with Windows 7, and it comes back to the applications and interface narrative. Sure, users quickly adapt to Windows 8, but Scott says that once you've gone to Windows 8 and Metro, he doesn't advise that you go back. "The thing you don't want to do is run Windows 8 on one device and Windows 7 on another," Scott said.

Poste Italiane's Vincent Nicola Santacroce, meanwhile, reckoned his use of Windows 8 has so far been "as a toy", with execs using apps for stock information and news. The staffers he calls Poste Italiane's "more generic users" - the salespeople - run Windows 7 desktop PCs.

"In the first five to six months we have been running it with top and middle management... so that's people with certain user experiences and [who] don't drill down into big process applications. So if there are issues, they will come out in the next couple of months as we start to extend it to people who are at a lower level," Santacroce said.

Ultimately Microsoft's s carefully orchestrated pitch about enterprises rolling out Windows 8 and working with ISVs on application support may prove irrelevant, and not just because companies are going to Windows 7 - an operating system that will displace Windows 8 as the standard enterprise platform.

It may prove irrelevant because Microsoft rather hopes to force the hand of the corporate IT department by targeting consumers with Windows 8.

Microsoft hopes Windows 8 and devices like Surface will ride into business by capitalising on the Bring Your Own Device (BYOD) trend that has seen iPads and iPhones force their way into the workplace.

If Microsoft is successful, the irony is that many of those enterprisey features that Microsoft touted in London this week - Windows To Go, Direct Access and so on - won't matter because they only come on Windows 8 Enterprise, which only comes under a Microsoft volume licence. Such licences do not come with the Windows 8, Windows 8 Pro or Windows RT. ®