Windows Vista forum

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Running XP from USB harddisk....


I like to run XP on a Vista machine (Acer 5720).

There are many info on installing and running XP on a USB HDD....


My question is:

If I put a new, blank HDD in my laptop and install an XP on it, can it boot later as an USB HDD after I have put back the original Vista ?

Of course, instead of the multiboot option I set the boot device in the BIOS....

So ... Would that work?

Does XP install itself "remembering" that it sits on an IDE HDD or just happy to find the MBR on the boot device ?

Thanks !


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In reply to: Running XP from USB harddisk....

Windows, unlike most Linux distros, is not designed to run for an external hard drive, and 99.99999% of the time it will fail. (Microsoft debated adding such functionality, but decided it was not worth the effort.) There are many who claim to have done it successfully, but it requires modification of system files (without tutorial) and just the right hardware (which no one can specify in advance) to do so. Thus, the odds are overwhelmingly against it. Also, note that OSes are not automatically detected...the first step would be to install XP while the HD is internal, then move it externally and reinsert the Vista drive, using VistaBootPRO to add the appropriate reference to XP, but due to the above it would still fail.


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Booting XP from USB - when does it checks the internal HDD ?

In reply to: No...

Hi John, thanks for the input !

I have seen some encouraging signs, that's why I going to try, but first I going to get some more opinions.

I think, if from the BIOS settings it boots from the USB drive, it wont know about Vista on the internal HDD before the loaded XP looks around....

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Basic process...

-> System BIOS launches the boot loader.
-> The Windows Boot Loader (Vista's) loads the list of installed operating systems from the BCD store.
-> If only Vista is detected, it loads automatically; If multiple OSes are installed it displays a list.
-> If an entry for a previous version of Windows exists and you select it, Windows Boot Loader loads NTLDR (XP's boot loader).
-> NTLDR then loads XP.

In order to attempt to run an OS from a portable disk you must either change the BIOS settings such that USB is the primary boot option or add an entry to the BCD store regarding XP's existence and location. (When you encounter failures there you'll understand why it's generally said not to work.)


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