I am considering upgrading a computer from Windows 7 Home Premium to Windows 10.

However, before I start the process, I have a couple questions hopefully users here can answer:

1) Does the upgrade require user registration info? The computer came with Windows pre-installed, years ago, and I really don't like the prospect of having to turn my place upside down looking for the serial number or activation number. Is any of this info required for the upgrade?

2) Does the upgrade overwrite everything (i.e., effectively re-format the computer)?

From what I've read, the upgrade uses your existing registration (available from your current installation). The upgrade can be done (supposedly) without having to reinstall any of your existing apps. Once you have done the upgrade, a hash value of your current basic hardware is sent to Microsoft where it is used to identify your computer. Once MS has this value you can (if you like) do a clean install and your computer will be recognized as legitimate. As with any major procedure of this type, do a full backup before starting.

However, you should check the links in this thread, as well as this article and also this article. Windows 10 has so many issues with privacy that I would never consider installing it in its current state.

2) Does the upgrade overwrite everything (i.e., effectively re-format the computer)?

I'm gonna be very brutal. Get ready.

Microsoft has been ranted over about some problems with privacy before (NSA surveillance along with many others). There's also lots of articles on how Windows 10 has lots of leaks due to your privacy. And it's super-weird that Windows 7 and Windows 8.x users, are getting free copy of Windows 10. Especially when you got charged for it about 80 euro/100 dollar (pure guess). Smells lots like sponsoring.

I'm not saying it is true, but for me it sounds like Microsoft got paid to the hand to spread out software, that is there just to keep Big Brother above your head. No real improvements whatsoever. I had installed it once, it destroyed HDD physically (no data retrievable, no source of problem found), but then again I was stupid enough to install Windows 10 Developer Preview, so it's my bad. Still lots of leaks due to privacy, and as I mentioned, the scandal that happened (if it did) some time ago with Microsoft implementing spyware for NSA.

If I will have to install Windows 10 on my computer as main OS. They would need to pry Windows 7 and Linux out my dead and cold hands.

So technically it overwrites your right to privacy. Because it's not about conspiracy mess anymore, it has been proven that Windows 10 leaks your privacy. Reverend Jim, just pointed just a small fraction of them.

Even as far back as Windows NT 4 (Service Pack 5) there was a variable name, _NSAKEY. I'm not saying this is what it looks like, but it sure looks like what it looks like. You can be sure that when the NSA says they are no longer spying they really mean that they have gotten better at covering it up so I can only imagine that _NSAKEY is still present, but under a less obvious name.

Or try reading this from Paul Thurrot for a balanced look at the Windows 10 privacy argument...

I'm not saying it is true, but...

Ah, enough said. File under conspiracy theory nutjobs.

Paul Thurrot makes several good points. Indeed, perception often shapes reality. So does reputation and Microsoft's reputation is certainly not stellar. It doesn't help when certain settings (except for Windows 10 Enterprise) can be set to "disabled" and still send information back to Microsoft. It also doesn't help when privacy settings are scattered, seemingly willy-nilly, throughout the system.

Do you recall a few years back when Microsoft said that the reason for the price difference between Windows Server and Windows XP was that they used a different core code set? And then someone showed that the only real difference was in software settings. I don't fault Microsoft for charging more for a server version of Windows. Many devices come with capabilities that are disabled unless you pay for them. I do fault Microsoft for lying about it. Reputation is important and if you think you are so big that reputation doesn't matter then you have a serious problem.

1) no, it automatically detects and verifies your Windows 7 or 8 key and converts it to a Windows 10 key (or maybe it's the same key).
2) no, as long as you upgrade to the same language version Windows as your old version (so English->English, or German->German, if you go German->English it keeps your data but you'll have to reinstall your applications).

that "NSAKEY" thing was a hoax, an attempt (spread about by the "fancy" "I hatez Micro$soft" crowd to discredit Microsoft.
So was pretty much everything else people hold against them.

"It doesn't help when certain settings (except for Windows 10 Enterprise) can be set to "disabled" and still send information back to Microsoft."
More nonsense. If you're using a Microsoft account it synchs that of course. If you use Cortana to search the internet it sends your queries of course. Etc. etc. etc.
People expect to be able to use internet based services without sending information over the internet, THAT's the real problem.
Yet for whatever reason they don't complain when it's not Microsoft but Google or Apple...

Oh boy, I started off-topic which created chain of off-topic posts.

Can we be done yet? All of us have different experiences and different sources. And we all can agree that even if shared it all, we wouldn't change our minds because humans are damn stubborn.

The topic had two questions, which are totally unrelated to our discussion. Skip it guys, this is DaniWeb.

From zdnet

Windows 10 goes one very large step further.

When you upgrade from Windows 7 or Windows 8.1, the Windows 10 setup program checks your current activation status and reports the result to the activation servers. If you're "genuine" (that is, properly activated), the Windows activation server generates a Windows 10 license certificate (Microsoft calls it a "digital entitlement") and stores it in conjunction with your installation ID and the version you just activated (Home or Pro).

It didn't need a product key to do that activation. All it needed was the proof from the Software Licensing Manager utility that your underlying activation was legit.

You can now wipe that hard disk completely, boot from Windows 10 installation media, and install a squeaky clean copy.

The Setup program asks you to enter a product key, but in a major change from Windows 8 and 8.1, it allows you to skip entering that key.

From wikipedia

It was already known that Microsoft used two keys, a primary and a spare, either of which can create valid signatures. Microsoft had failed to remove the debugging symbols in ADVAPI32.DLL, a security and encryption driver, when it released Service Pack 5 for Windows NT 4.0, and Andrew Fernandes, chief scientist with Cryptonym, found the primary key stored in the variable _KEY and the second key was labeled _NSAKEY.

Microsoft denied the speculations on _NSAKEY. "This report is inaccurate and unfounded. The key in question is a Microsoft key. It is maintained and safeguarded by Microsoft, and we have not shared this key with the NSA or any other party." Microsoft said that the key's symbol was "_NSAKEY" because the NSA is the technical review authority for U.S. export controls, and the key ensures compliance with U.S. export laws.

Richard Purcell, Microsoft’s Director of Corporate Privacy, approached Campbell after his presentation and expressed a wish to clear up the confusion and doubts about _NSAKEY. Immediately after the conference, Scott Culp, of the Microsoft Security Response Center, contacted Campbell and offered to answer his questions. Their correspondence began cordially but soon became strained; Campbell apparently felt Culp was being evasive and Culp apparently felt that Campbell was hostilely repeating questions that he had already answered. On 28 April 2000, Culp stated that "we have definitely reached the end of this discussion ... [which] is rapidly spiraling into the realm of conspiracy theory" and Campbell's further inquiries went unanswered.

Yes, this all boils down to whether or not you believe Microsoft. As I've said before, Microsoft has done little to earn my trust and a lot to destroy it.

People expect to be able to use internet based services without sending information over the internet, THAT's the real problem.

I certainly do not expect that. What I do expect is to be able to decide what information I will be sharing. I have windows in my house. I realize that these windows allow others to see in, however, I get to decide what the see. I can also close my drapes/blinds with the expectation of privacy. I would certainly consider it a violation of my privacy if after doing that people were still able to see in.

ars technica has an interesting article on this. The article also points out that even if you have no live tiles active, live tile info is still periodically sent to your computer.

Microsoft has crippled Solitaire and tured it into adware/crapware unless you pay a monthly fee to disable the ads. Microsoft is increasingly seeing Windows users as a product to sell rather than as valued customers. As I said, they have done more to destroy my trust than to earn it.

No it's free and it will save your data on PC. Don't worry about this