Windows 8 used 280MB of data while Windows 7 used 400MB to run, the implication being that users of older machines won't be forced to upgrade to a new PC if they want to upgrade to Windows 8.
The figures, Sinofsky said, should quell fears that Microsoft would "add layers" and "slow down" the operating system and make it a clunky user experience for users of older machines.
"We're not building layers on layers," he said of the new Metro user interface. Everything is built into Windows.
The company is unveiling the Windows 8 operating system developer's preview and is also preparing to demonstrate some of the touch-enabled devices you'll be able to use with the upgrade.
We've got a full Windows 8 hands on review, so check that out for our initial impressions on Microsoft's complete re-imagining of its classic OS.
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A technology journalist, writer and videographer of many magazines and websites including T3, Gadget Magazine and TechRadar.com. He specializes in applications for smartphones, tablets and handheld devices, with bylines also at The Guardian, WIRED, Trusted Reviews and Wareable. Chris is also the podcast host for The Liverpool Way. As well as tech and football, Chris is a pop-punk fan and enjoys the art of wrasslin'.