With a 128GB Model, iPad Throws Down to Surface | MIT Technology Review

Also note that the 128GB Surface Pro is more of an ~83GB device, in terms of free storage; AllThingsD notes, in And the 32GB Surface Pro Will Have Just Enough Storage to Display the Start-Up Screen, that Surface customers can regain storage space by deleting a recovery partition

"The initial idea behind the iPad was a lightweight, super mobile computing device that could access the cloud for storage and streaming media. But Apple is making a case for the iPad as a full-blown productivity and business device. Cupertino says that “virtually all” of the Fortune 500 and over 85% of the Global 300 are “currently deploying or testing iPad.” With 128GB at your disposal, the range of projects you can engage in using local storage expand: you can edit a movie, mix a song, design a building.
Many observers are calling this a run at Microsoft, whose Surface tablet has marketed itself as the device that will most effectively switch hit between a passive-tablet mode, and an active-laptop mode. If you’re really dedicated to making your tablet feel like a laptop, your best bet is still probably with the Surface or with the upcoming Surface Pro, which runs a full version of Windows 8 Pro, effectively mimicking a desktop environment in a mobile form factor."

With a 128GB Model, iPad Throws Down to Surface | MIT Technology Review