I used to install Windows 7 -- now admittedly, it was onto VM's, not on actual hardware, so I don't know if the OS installation is smart enough to know it's being installed on a VM and leave stuff out -- but it was less than 10G. So the mistake was installing a full-blown Windows 8 install instead of their tablet software, or making some sort of "pro" version of their tablet software, or not trimming out the fat -- I mean, I bet half of that is for fonts and foreign language versions of stuff. And how many drivers do you need if you control the hardware?