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I have a Dell Inspiron 6400 laptop that's a few years old. I've just bought a new 320GB HDD for it, and am looking to rebuild it. I still have the OEM DVDs from Dell that Windows XP was installed with, but I'm concerned that it won't activate with that license key because the HDD serial number will be different.

Does Windows Product Activation care about the HDD serial number (and thus I have to buy a retail copy of Windows 7), or should I be okay?

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There is a 99% chance it will activate over the Internet without a problem.

If it doesn't, it will give you a phone number to call Microsoft (in your locale), and you can explain what happened and they will help you activate it.

Here's a blurb on changing hardware and activation, from Microsoft's site under "Myths About Activation":

Product Activation keeps users from changing or upgrading their hardware.

Not true at all. Users can change or upgrade their hardware. One of the forms of piracy that Product Activation guards against is hard disk imaging. Not all forms of hard disk imaging are illegal. In the case where a pirate copies data from one PC hard drive to another to illegally run the software on two PCs, Product Activation stops that by forcing the copied software to be reactivated. It does so by comparing the hardware on which it was activated to the hardware on which it is now being booted. If the hardware is substantially different, then reactivation is required. If it is the same or similar, then the software will continue to work. Those who upgrade their PC's hardware substantially may be asked to reactivate. Reactivation for this reason is easy and can be completed by contacting Microsoft to obtain another confirmation ID.

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+1 Nice detailed explanation – Dave M Aug 11 '11 at 12:08

You will be fine. If for some reason you can't activate through internet you will be provided with a Microsoft phone number and a bunch of numbers so you simply call them and they will provide you with the activation code.

I have done it several times, it always worked, and I only had to call Microsoft activation once.

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+1 Same here. Done this many times and seldom have to call MS. – Dave M Aug 11 '11 at 12:02

I successfully reactivated an OEM XP after upgrading my hard drive, no problem, didn't have to call Microsoft.

The algorithm they use for activation has a tolerance to allow for some hardware changes. Given that it's a laptop, your hardware probably hasn't changed much (if at all) since it was new, so changing the hard drive won't be enough to cause trouble with reactivation.

For more details on the activation algorithm and its tolerance for changes, see

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