Now that the Surface Pro is officially on sale (although the 128 GB version seems to be in short supply online) Microsoft has now updated the Surface website with its official storage numbers for the 64 and 128 GB versions of the Windows 8 Pro tablet.
The numbers shown on the Surface website are a tad confusing, however. That's because, as ZDNet's Ed Bott points out, the page uses the binary system to display how much space is available on the tablets. If you go by the page, the 64 GB version has just 59 GB of total space, with a total among of available space listed as just 29 GB if you take away the Windows 8 Pro and included apps and the system recovery tools.
The 128 GB version has just 119 GB of storage, according to the binary system, with 89 GB of space available after the Windows 8 Pro and included apps and the system recovery tools are taken into account.
If you use the decimal system to measure storage space, things look a lot better. Then the 64 GB version has 32 GB of available storage, and the 128 GB version has 96 GB of file space. Owners can free up another 10 GB of space if they move their system recovery tools over to an external flash drive.
Source: Surface website