Much has been made of the Surface Pro's limited storage capacity, and for good reason. The 64GB model has precious few gigabytes available to the user, especially when compared to Android- and iOS-based tablets with similar amounts of flash. Windows 8 looks awfully bloated next to those tablet operating systems.
Maybe it's not so bad as we think, though. ZDNet's Ed Bott has crunched the numbers and determined that the Surface Pro's free space is awfully close to what's available on the MacBook Air. He used the 128GB versions of both devices and discovered that the MacBook offers 92.2GB of user-accessible storage, while the Surface serves up 89.7GB in its default configuration—a difference of just 2.5GB. Users can move the Surface Pro's recovery partition to a USB drive, boosting the user capacity to 97.5GB. The capacity used by OS X's recovery partition can't be reclaimed, however.
Those numbers are based on 1GB equalling 1,073,741,824 bytes, by the way. Windows and OS X report storage capacity differently, with Microsoft favoring the old-school base-two system and Apple switching to a base-10 format in Snow Leopard. Bott goes off on a bit of a tangent about how the change causes OS X to report higher capacities than Windows for the same number of bytes, but that's another debate for another day.
While Bott hasn't run the numbers for 64GB versions of either system, he suspects they'll have similar amounts of user-accessible storage. In a lot of ways, the Surface Pro is more like the MacBook Air than the iPad, so the comparison is a fair one. And, unlike the iPad and 11.6" Air, the Surface Pro has a built-in microSDXC slot capable of expanding its storage capacity.