I'm building a budget PC for my mum, and have upgraded her mobo, processor, RAM and PSU. I wanted to keep her hard disk drive as is, however changing the PC so much will obviously mean that I can't just plug in the HDD and switch it on. Unfortunately, the version of XP that came with the PC is OEM so doing a repair install to get it up and running is not an option.
So...I'm now thinking that I may as well upgrade her OS to Windows 7. Will I be able to use an upgrade version of Windows 7 (cheaper) with the new PC spec as XP is already installed on the HDD, or will I need a full copy and install it fresh on a new HDD? Could I install Windows 7 before upgrading the hardware, and then reactivate it when I put the HDD in the new PC?
You can purchase the less expensive upgrade copy of the software since you'll be replacing a previous, licensed version of Windows.
But you can't use it to do an "upgrade", you'll have to do a full installation and then reinstall all of the other software.
IMHO it would be a lot easier to install Win7 when you swap computers - if you try to install it on the existing system then you're likely to have issues because of the different hardware on the new system.
I am replacing most of the components except the HDD.
Instead of buying a new version of Windows XP, I thought I might as well buy Windows 7. Can I use the upgrade version, even though I will be installing it on a computer which Microsoft will consider to be "new" and not the computer that XP OEM is licenced to? Or will I need to buy a full version of Windows 7 as I have changed the PC?
I don't know if there's an "official" answer for the question you're posing. It would certainly be against the license agreement to move XP itself to new hardware. But IMHO purchasing an upgrade and using it on a different machine seems reasonable.
I say this because to the best of my knowledge, "upgrade" versions are licensed the same way a retail kit is (in other words, there's no such thing as an OEM "upgrade", since an actual Original Equipment Manufacturer simply buys licenses for the current version). And also, to the best of my knowledge, for an "upgrade" kit there's no restriction on what type of license the previous version has. If there was, then you'd see "OEM Upgrade" vs. "Retail Upgrade" SKUs.
If someone knows differently, then please chime in.
Certainly from a technical point of view it will work.