This isn't news.
They won't be running demonstrations on the actual console hardware yet because it a long time until release. They are still working on testing and development. They would be stupid to demonstrate on unfinished and unstable tech.
Running Windows 7 is sensible as it is more established and therefore more stable. Again it would be stupid to run a demonstration at E3 on anything less than the most stable platform you have access to. The Xbone SDK would have been designed to run on Windows 7 as it was made and in use a long time before Windows 8 was released.
They aren't using PCs with the same hardware as the actual console as it would not be powerful enough to run as well as the consoles due to the amount of direct to metal programming relied on to gain efficiency.
They won't be running demonstrations on the actual console hardware yet because it a long time until release. They are still working on testing and development. They would be stupid to demonstrate on unfinished and unstable tech.
Running Windows 7 is sensible as it is more established and therefore more stable. Again it would be stupid to run a demonstration at E3 on anything less than the most stable platform you have access to. The Xbone SDK would have been designed to run on Windows 7 as it was made and in use a long time before Windows 8 was released.
They aren't using PCs with the same hardware as the actual console as it would not be powerful enough to run as well as the consoles due to the amount of direct to metal programming relied on to gain efficiency.