Using another machine's HDD to downgrade Vista to XP?

If you have two machines A and B, of the same model and mostly the same configurations, where A has been downgraded from Vista to XP, B has Vista. Can you simply replace B's HDD by A's HDD to run XP on B?

 

Sure. Most likely, it will work.

 

I think it will work if both are completely identical.

 

As stated, if its the same hardware in both machines you'll be fine.

 

Thanks. What if they differ in some parts that may have different drivers? Download the drivers after replacing the HDD?

 

if it doesn't bluescreen it works and you can install needed drivers afterwards. it may fail during the boot process, though (if hw is not identical).

 

It may, or may not, work depending on whether or not the software is from an OEM license or a retail license and, if OEM, on how diligent the manufacturer was in implementing the copy protection mechanisms (from the description, it sounds like software that was preinstalled under an OEM license).

With _Vista, Microsoft has added further wrinkles to the original protection mechanisms that were used to lock an OEM version of XP to a particular machine. For OEM versions of XP, activation was tied to data contained in the BIOS and, as long as the XP copy found the same data in the BIOS on bootup the copy would boot, which meant that in practice you could change any component other than the motherboard without requiring reactivation; if the motherboard was changed it would still boot provided that the new MB was from the same producer and contained the same data in the BIOS. For a more detailed description, see this article on MS' Technet.

A retail version would be "locked" to its hardware by generating a hash from various values located on the components, including the processor serial number, hard drive volume serial number, and the MAC address of the network adapter. The algorithm used permits several components to be changed without requiring reactivation. Dowever, different components are weighted differently, with the greatest weight given to the network adapter, meaning that if you changed the network adapter you could change fewer other components before reactivation is required; also, once a component is changed, further changes to that component do not count as a "change" for purposes of the algorithm. A more detailed explanation is here.

For OEM and retail versions of _Vista, the same basic approaches are used, although in the case of the OEM versions the BIOS-locking mechanism has been beefed up in response to various cracks and work-arounds (including some brave souls who are skilled/foolish enough to actually edit their BIOSes to provide the requisite OEM data).

Thus, in your case, since you appear to have an OEM pre-installed version of _Vista, that should mean that the copy of _Vista that was originally installed and which was subsequently downgraded (and will therefore continue to affect the determination of genuineness, or not, as far as I can tell) will continue to function the same so long as it continues to find the right data in the system BIOS when it boots.

Since you will be moving the hard drive to a machine that was manufactured by the same OEM, it is very, very likely that the installation will continue to boot without problems (OEMs seem to get a bit lazy about the BIOS locking and my guess is that the same OEM data will occur in almost every BIOS put out by a single OEM).

Further, since your copy appears to be OEM not retail, your activation should not be affected by changes in any of the components other than the motherboard.

The fact that you have a copy of XP that was installed using the End-User downgrade rights provided with certain versions of _Vista could be a complicating factor depending on whether the media from which the copy of XP was taken was an OEM disk or a retail disk.

If it was an OEM disk, then it seems that the BIOS locking mechanism will still be in place, in which case the installation will continue to operate when moved so long as the same OEM data shows up in the BIOS of the new machine.

If the XP installation was made using a retail disk, then it's possible that you might have been shifted over to the hash-method of validating the hardware on which the XP copy is installed, in which case the installation would not work once the hard drive is placed in the new machine - because too many of the components would have been changed, resulting in the need for reactivation.

All of which raises the interesting possibility of a conflict between validation methods if an OEM version of _Vista (the only type that qualifies for downgrade rights) was downgraded to XP using a retail XP disk.

If both validation methods continue to work, that would result in the _Vista validation saying the system was ok - because the same BIOS data was found - and the XP validation saying the system was not ok - because the hash derived from the system's components would no longer be valid. That might result in a situation where the OS validates each time, but the annoying pop-up balloon keeps popping up saying that the OS copy was invalid and might be counterfeit - as has apparently been happening to some users from what little I've read on the subject.

Anyway, my guess is, in your case, that the OS installation on the hard drive should continue to function when it's moved to a second system because the OS copies are most likely both OEM versions, and the new system will almost certainly contain the right data in the BIOS since it's from the same manufacturer as the system from which the drive is being taken.

 

Shyster1: I mean if both are from the manufacturer.

If it can be done just by replacing the HDD, is there anything else needed to be done at all, or simply: 1) take out the Vista HDD, 2) insert the XP HDD, 3) turn on the machine. Voila it goes! ?

 

You have to make sure all of the internals are the SAME model, and have the SAME drivers. If that is the case, then yes it will work. (Basically, if you have two of the same model laptop's with the same internals, it will work, but if the models are different, then no.)

 

So the worst is just it may not work? Could it cause any harm/damage? And when you say it may not work, how will that manifest? Press the power button and nothing happens, or it works mostly but just some components without appropriate drivers will not work?

 

If it works, it'll just work; if it doesn't work, it'll tell you in one of three ways: (1) it'll bluescreen at startup, provide you with a stop code, and then sit there until you restart it, (2) it'll boot up and then hit a driver conflict it cannot remediate, and it'll bluescreen as above, or (3) it'll constantly pop up a dialog box saying that such-and-such had an error and needs to close, and will then ask if it can send an error report to Microsoft.

It's not going to damage anything physical - if you have the wrong driver for a particular device, that device simply won't work, and it'll be flagged as a problem device - of course, if that device happens to be something like the chipset, then it'll probably bluescreen.

It might change the configuration of the OS installation to deal with any hardware differences between systems A and B, and those changes might mean that it'll start bluescreening or having other problems if it's ever put back into system A.

 

Thanks. I suppose the differences between the two machines in RAM capacity and HDD storage should not matter?