If you're interested in privacy and have Windows 8 Pro, you can use Client Hyper-V and Differencing Disks to make what is effectively a "read only" system. You boot into the VM, do whatever it is you have to do, then shred the differential [0].

Alternatively just encrypt the VM[1].

Alternatively again just run a Linux "Live OS" from a DVD and pull the power to "wipe."

Alternatively ad-infinitum make a Windows To Go Thumb Drive and smash it with a brick when you're done.

[0] http://technet.microsoft.com/en-us/library/cc720381(v=WS.10)...

[1] http://www.virtualizationadmin.com/kbase/VirtualizationTips/...