Transfer Windows from one HD to another?

[SaviorSelf]

Computer amateur here so bare with me. I'll try to outline some things to hopefully make this a little easier to describe.

Computer A = Works Great.
Computer B = Hunk of shit recently salvaged.
Hard Drive C = Hard drive that was in Computer B.
Hard Drive D = My old hard drive from an old computer that got scrapped.

While going through the motions of buying an external hard drive, I just ended up with buying another 23" LCD screen for [Computer A]. I had 2 left over screens that I put to the side. I recently found [Hard Drive C] and while trying to get whatever files off it, I just thought that I could potentially use it as an extra desktop for forum browsing or anything I wouldnt want to risk [Computer A] with.

I plugged [Hard Drive C] into [Computer B] and just as I thought, it was slow as shit. It literally took 20 minutes for Internet Explorer to open up. About an hour later I gave up trying to navigate it, unplugged it, connected it to my external hard drive on [Computer A] and just took the files off I needed. I wasn't sure of what I was doing at the time, but from this computer I formatted [Hard Drive C] and what do you know, it really did erase everything (including Windows XP). It was only a 40GB HDD, so whatever, no loss I suppose.

I plug in [Hard Drive D] and get up to the login screen, where I'm greeted with "Windows is not activated, click here to continue", when I used this hard drive on my old computer for years. Yes it used to work, not sure why it doesn't now. Going through the screens, it then says to register it needs a phone line. It was wirelessly and hard wired connected, but still prompted for a phone line. I don't have one that could get to the computer. Is there any other way around this? Why doesn't it feel like working now?

If [Hard Drive D] cannot be registered, is there a way I can transfer my copy of Windows from [Computer A] to [Hard Drive C]? Or if need be, to [Hard Drive D]?

Sorry if it was confusing, but hope someone understands.

[Ratatapa]

The thing about XP is that when you change 3 HArdware material that is important, exemple Processor, memory etc you will need to reactivate windows it's sad but hey that's M$ for you

[Neb]

The thing about XP is that when you change 3 HArdware material that is important, exemple Processor, memory etc you will need to reactivate windows it's sad but hey that's M$ for you

Not totally true I changed almost all my hardware and it asked me to reactivate I just called them and bitched and the gave me an activation code ^^

[Ratatapa]

You did reactivate it tho, so i was right

[Mafai]

just call to reactivate and say you reformatted. you will usually get some guy working from home that could care less. loud noises in background kids screaming, last 2 times i did this that was the case.