When Windows 10 is released on July 29, it will not be available on new PCs. Microsoft is still finishing its work on the software in order to meet its deadline and PC makers are unlikely to receive a final version of Windows 10 until later this week. Those PC makers must still test the software and make sure it works with their devices.

Since Microsoft is working on the operating system right up to the end, new PCs won't have Windows 10 preinstalled for a little while longer. Yusuf Mehdi, VP of Windows and device marketing, confirmed new PCs would probably not include the software.

Microsoft is also using a phased roll out for Windows 10 and that means Windows Insider Program members will be first to receive the update.

Dell is the one PC vendor that will likely have Windows 10 on new computers almost immediately after release. Preorders for some of its PCs should ship out on release day.