You lie about Windows taking 23 GB of space.
I found this... from Microsoft.com
How much storage space do I have?
Heres how much storage you have available out of the box:
Surface RT
The 32 GB Surface RT has approximately 15 GB storage available for user content (17 GB used up by default)
The 64 GB Surface RT has approximately 45 GB storage available for user content (19 GB used up by default)
Surface Pro
The 64 GB Surface Pro has approximately 28 GB storage available for user content (36 GB used up by default)
The 128 GB Surface Pro has approximately 85 GB storage available for user content (43 GB used up by default)