Microsoft has added Dell and Lenovo to its list of Windows RT device vendors. Redmond has already named Samsung and said that the three are developing ARM-based tablets which will run the RT edition of Windows 8.

Microsoft said that it has provided the vendors with the Release to Manufacturing (RTM) builds of both the x86-based and RT editions of Windows 8. General availability is scheduled for 26 October. Microsoft ecosystem and planning vice president Mike Angiulo said in a company blog post that PC manufacturers will be unveiling their products as we approach the Windows 8 and Windows RT launch.

He said that the spectrum of form factors and peripherals being developed to meet each customer’s computing needs was unique in the IT industry. Asus is also planning to support the Windows RT platform with its Tablet 600 system.

Microsoft said it was working with Nvidia, Qualcomm and Texas Instruments to develop ARM CPUs for use with Windows RT.