EH-Net

I'm trying to recover cached credentials from a forensic image.  I'm using PRTK to crack secuurity + system file.  It's my understanding this could take a week.  Can anyone suggest a better technique?  I know Cain is supposed to be faster, but can you export files from the forensic image and import into Cain?  Whenever I run Cain, it appears to only be able to obtain cached credentials from the host computer.