Similar to a core install in Windows Server.

On my machine I get about 1/3 the number of processes in Task Manager.

Everything works, but without all the bloat of a desktop I get a noticeable boost in performance.

Hash rates are similar, but there I see less lag when using the computer for other tasks.

You can edit the Windows registry.

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon

Edit SHELL replacing windows.exe with cmd.exe

Reboot and you get no desktop.

You get a command prompt, just like Safe Mode, but with all your drivers.

I gave up trying to find a way to install windows 7 to USB.

I don't think  it can be done. At least not easily.

You can download Windows 8 Enterprise evaluation edition free from Microsoft.

Then you can do a Windows to Go installation.

The evaluation edition expires in 900 days (90x10) if you use slmgr -rearm.

http://www.computerperformance.co.uk/win8/windows8-skiprearm.htm

http://arstechnica.com/business/2012/03/ordering-windows-to-go-how-to-create-a-bootable-windows-8-usb-thumb-drive/

I have my backup wallet on a Tails live USB.

 https://tails.boum.org

 First you burn a DVD. Booting from the DVD you can then use a Tails wizard to make a USB with a LUKS encrypted persistent partition.

 I can't get a miner to run on linux yet, so I do my mining on a Windows to Go external hard drive with BitLocker full disk excryption.

http://arstechnica.com/business/2012/03/ordering-windows-to-go-how-to-create-a-bootable-windows-8-usb-thumb-drive/

 I have plug and play hard drives which I only insert when I'm playing video games.