How do I get the operating system HDD to run from an external USB

Ok, my girlfriends computer blew up a whiel back and I have her HDD running in an external USB enclosure, how can I get my computer to run this HDD so I can take off her passwords and save her files?

 

I don't know what this 'USB enclosure' is. You don't need or want your system to 'run' that HDD, just recognise it as a plug in drive.
But all you need for that is a USB to IDE cable - the IDE end plugs into the HDD and the USB to your functioning system.
You can then save any data you want from that HDD.

 

So a USB HDD enclosure is just like an external HDD, but you can replace the HDD with any that you want to use.

My problem is I want to run the XP off this External drive and the HDD was password protected, I have the passwords I just need the access.

 

Every time an OS is installed certain parts of it are customised to work with the computer it is installed on. As a result, the OS on the external hard drive will likely as not fail to work on your PC.

If you just need to get the files off, as BriJack said, all you need to do is plug in the external HDD using USB and transfer the files.

 

WOW ID love to follow that protocol for nearly a thousand + photos and the documents, any other suggestions? before I start