A bit more "fine print" about the free Win 10 offer from MS. It's free for all 7 and 8 users, except Enterprise versions. Presumably those users will get it from their "Enterprise." This appears to be more of an upgrade rather than a complete system trashing, since it will require that the Windows Upgrade feature be turned on and MS warns of possible "ISP charges" resulting from what is likely to be a massive download.

Fine Print:

*It is our intent that most of these devices will qualify, but some hardware/software requirements apply and feature availability may vary by device. Devices must be connected to the internet and have Windows Update enabled. ISP fees may apply. Windows 7 SP1 and Windows 8.1 Update required. Some editions are excluded: Windows 7 Enterprise, Windows 8/8.1 Enterprise, and Windows RT/RT 8.1. Active Software Assurance customers in volume licensing have the benefit to upgrade to Windows 10 enterprise offerings outside of this offer. We will be sharing more information and additional offer terms in coming months.