how to virtualize a old installed disk

Hello

I use vmware Workstation 9, recently i have installed win8 to a new disk on my PC, andI haveto keep the old installed diskwithwin7.

Now i want virtualizing my old win7 Installation from old disk over a usb Interface, that I can usethis one on vmware Workstation 9.

Waht th best method to virtualizing my old System disk ?

Thanks for help

Ben