Boot window from external hard disk

Yes, it is possible to use the external hard drive as a total replacement / backup unit if your internal C drive crashed and you were no longer able to boot into Windows. This is called making a mirror image of your hard drive.

You can do this if:

a) your external hard drive is as big or bigger than your internal hard drive, and

b) you use a disk image like Acronis True Image to make a "mirror copy" or "disk copy" from the internal hard drive (C drive) to the external USB drive (D drive, for example). A mirror copy essentially copies the *entire* drive from one to the next.
Acronis here:
http://eu.acronis.com/homecomputing/products/?source=eu_google&ad=acronis&s_scid=acronis|947440254&gclid=CO-X66_7y5MCFQUKuwodhS7SqA

Also very important:

You will need to modify your boot sequence so that your external hard drive does not always try to boot first. Otherwise, you will be booting off your external hard drive after your first mirror copy is completed. This is not what you want, because any changes to the system will be done to your backup drive instead of your internal PC hard drive.

You can change your boot sequence by going into your computer's BIOS (Basic Input Output System). On most computers, the BIOS can be activated by holding down either the DEL or the F2 key when you first turn your computer on. Normally there is a message displayed at the bottom (or top) of the screen to "Press XXX key to enter CMOS / System Utility", etc.

Once you're in the BIOS, look for a section like "Boot" or "Startup". Since not all BIOS's are the same.

When you're in the Boot menu, ensure that the C drive boots first, then the CD/DVD ROM, and then the USB drive (note that your external USB drive will need to be plugged in and turned on in order for it to show up in the list of bootable options).

Please post back if you have any more problems or questions.

I agree with Peconet Tietokoneet's advice with the exception of his recommendations for boot order.

If the boot order is:

Hard Drive
CD/DVD Drive
USB Drive

then you cannot boot from the USB drive because the BIOS will see the HD first, and boot from that. Therefore, I would recommend that you use the following boot order in your BIOS menu:

USB Drive
CD/DVD Drive
Hard Drive

This way, the BIOS will first energize the USB ports and look for the boot sector of the Master Boot Record (MBR) of your external hard drive. If the BIOS finds nothing, it will next search the optical drive(s). Finally, it will look for the [b]C[/b] drive.

Peconet, if I'm wrong, please post back and clarify this for [i]document1530[/i].

Rick/Portland, OR