As we've noted before, Windows 10 will be a free upgrade for existing Windows 7 and Windows 8.1 customers. It will also be free for Windows Phone users, but they will have to wait a little longer. Despite Windows 10 promising a universal platform, the phone version of the platform — one of seven planned versions — won't be out until later in the year. No word yet on pricing for enterprise or OEM buyers.
Hello World: Windows 10 Available on July 29 [Blogging Windows]