Windows 8 RTM in early August and on shelves in late October

Microsoft has confirmed that Windows 8 will hit RTM ("release to manufacturing") in the first week of August, with the next-gen OS expected to launch in late October. The news was announced at Microsoft's Worldwide Partner Conference 2012 in Toronto this morning by CFO Tami Reller, the first time the company has officially detailed the OS' release.

"Release To Manufacturing" means that Microsoft's hardware partners will get their hands on the final version of the software, ready to load onto their new devices. Any subsequent software changes will be released as feature packs or patches, with RTM basically presenting a deadline for Microsoft's software engineers to stop development work on the market-ready version.

Microsoft had aways said to expect Windows 8 in the second half of the year, but had been reluctant to pin the platform down any more than that. This summer, meanwhile, Apple will release its own next-gen OS in the shape of OS X Lion.

Sales estimates for Windows 8 machines are in the region of 375m new PCs in the space of the next year, according to Microsoft CEO Steve Ballmer. He described the OS launch as "the biggest deal" from Microsoft in the past 17 years.