Sometime after July 29, Windows 10 is going to start showing up in your business as employees either bring new PCs to work or upgrade their existing machines. Microsoft says it has had millions of reservations for the free Windows 10 upgrade. But despite the launch date, that's not going to happen overnight.
Who will get Windows 10? Who won't?
The new version of Windows will go out in stages, even to users who have pre-registered through the app in Windows 7 SP1 and 8.1. Members of the Windows Insider program will get it first, and once the feedback and telemetry from their upgrades show that there are no significant problems, other users who have reserved their download will start getting it and those downloads will be staggered as well. Windows Phones won't be getting Windows 10 until the fall, but users with small Windows tablets like the Dell Venue Pro 8 and the HP Stream 7 will get updates beginning on July 29.
You don't have to worry about upgrades happening on work PCs without you knowing about it. Volume licences of Windows don't qualify for the free upgrade, and the Get Windows 10 app won't appear on any PC that's joined to a domain, whatever the licence.
BYOD spells support
Most enterprises won't need formal management tools for Windows 10 yet, because enterprise deployments are likely some way off, even though the business editions of Windows 10 are shipping. Windows 10 Pro will be available on July 29, which is also when the evaluation version of Windows 10 Enterprise will be on MSDN. Windows 10 Enterprise (and the new Windows 10 Education edition) will be available for download on the Volume Licensing Service Center on August 1, because that's when Microsoft's Product Terms will be updated (this is the document that replaces both the Product Use Rights and the Product List).
If you have users (or members of your IT team) who are testing the Windows 10 technical preview on a PC that was running an Enterprise edition of Windows 7 or 8.1, they won't get a flight that takes them to the final version of Windows 10 Enterprise. They will need to install from the Windows 10 Enterprise media and activate with Volume Activation to get the final code.
But if BYOD is significant in your business, your help desk will need to get prepared to support users working with a new interface that's subtly different from both Windows 7 and Windows 8, and using the new Edge browser and the touch-optimized Office Mobile apps (including the mobile Outlook apps for mail and calendar) that are designed for on-the-go editing. You'll also need to think about Office licensing; those free Office apps are for personal use only and can technically only be used for business purposes if you have an Office 365 licence covering those employees (as is the case today for Office for iPad and Android).
Caution: new traffic patterns ahead
Your network team may see different patterns of traffic thanks to the way that Windows 10 uses peer-to-peer connections to share updates with other users rather than having every PC download the same update individually. And while Wi-Fi access points that are on a domain-controlled network won't be shared with a user's friends, they will be over other Wi-Fi connections if the Wi-Fi sense option is enabled. This doesn't share the password, so it's not a security risk, but it does shift the decision about allowing access from the network owner to the user. You don't want unauthorized Wi-Fi hotspots on business premises anyway, so this is just another reason to check the network regularly.
If you want to manage Windows 10 PCs as soon as they start showing up on your network, you can do that with Windows Intune and other Mobile Device Management (MDM) services that work with the MDM client that's built into Windows 10 (offering features like conditional access, configuration management and remote wipe), or by installing the relevant service packs for System Center Configuration Manager. You need SCCM 2012 R2 or the upcoming release to deploy Windows 10 to devices, but SCCM 2007 can manage Windows 10 devices.
If the devices that users are bringing to work are running Windows 10 Home, they're going to be getting both feature and security updates applied automatically. That uses the same rolling deployment model Microsoft has for Windows Update today, where not all PCs get the updates immediately in case there are problems.
Without the option of turning those updates off, the PCs that show up on your network are likely to be more secure. There's always the possibility that a problem update will affect your users and generate support calls, and if updates are labelled as cryptically as the hotfix bundles released for the final technical preview builds (which have no details of what fixes they maintain), troubleshooting might be more complex. But this is unlikely to cause significant problems, and it won't affect Pro and Enterprise versions, where you'll be able to control update deployment via Windows Update for Business. You can also opt for Current Branch for Business, which gets feature updates some months after they've been tested through the Windows Insider program and consumer installations, making it far less likely than any automatic updates will have problems by the time they reach your PCs. With Current Branch for Business, you can also postpone updates for up to eight months.
Paying to be up to date
Windows 10 marks a good time to think about Software Assurance. If you have SA, the upgrade to Windows 10 is included although you will need to maintain your SA status. If you don't have SA, you'll be able to buy Windows 10 Enterprise licenses in the usual way, and the in-place upgrade option may prove less time-consuming than the current option of wiping and re-imaging systems (you'll be able to deploy apps and configuration settings as part of the upgrade). But if you don't pay for SA along with those licenses, you don't get the same regular updates that Home and Pro users get for free.
With SA, you'll get feature updates; without it, you don't get those new features, just security patches, and eventually you'll have to pay for new Windows 10 licenses to bring your PCs up to date.
You'll also get the Windows 10 Enterprise Long Term Service Branch that you can put on mission-critical and sensitive systems where you don't want the configuration changing. With SA you get 10 years of support and new releases of LTSB that you can choose to move to every two or three years; without SA, you don't get the new versions of the long-term branch, and you only get five years of support.
That's substantially the same choice you've had before; paying for either just the current version of Windows or buying Software Assurance to give you the right to upgrade to the next version. But with the new Windows as a Service model, upgrading to get new features is far less disruptive, which may make Software Assurance a better value.