Booting with exernal hard drive

[J_I_M_B_O]

IS it possible to boot my pc with a laptop HDD in an enclouser attached to a usb port and then install windows on it incase my HDD fails?
I have seen the option to boot through the cd-rom drive and my camera card reader and the HDD is on the way from newegg and I was wonder if it'll appear as an option there

 

[unhappy_mage]

I think that will work. Can't hurt to try.