1. Possible Windows Old → Windows 10 Upgrade Paths
2. The Free Upgrade from Windows Vista to Windows 10240 via Windows 10130 (Insider Preview which used a generic product key - last build before the new Microsoft Product Activation Mechanism).
Windows must be activated and you must sign in with a Microsoft Account.
This upgrade path is valid until the 2nd of October 2015 when Windows Insider 10130 Expires effectively shutting the promotional gate to this free upgrade path. Once your system is a Windows 10 Device, Windows 10 will have 5 years mainstream support and 5 additional years extended support.
Windows XP/Vista are already obsolete.
- Windows XP reached End of Life in April 2014.
- Windows Vista never had support for Office 2013 so can be considered abandoned since 2013.
3. Video demonstration - Upgrade to Windows 10 from Windows Vista
https://www.youtube.com/watch?v=eeDx-wCWla8&feature=youtu.be