Changing PC's but keeping the same Hard Drive
So I am going to change PC's soon but I want to put my current Hard drive in the new one, My windows 8 is saved on this hard drive. If I take out this Hard drive with windows 8 on it and put it in the one I am going to buy, will windows 8 work or will I have to buy and install it again?
You may not have to buy Windows again. You will definitely need to reinstall because you'll need the drivers for the new mobo, chipset, etc.
I know MS uses the serial number of the CPU, hard drive, and something else I can't remember right now to develop a security key that checks that the install is a valid licensed install. After your install, it will bring something that says the current copy isn't a valid install but all you have to do is contact them and explain what you are doing and they will clear that message over the internet. I went through that the last time I had to replace a failed hard drive. That was on Win7 but they are probably doing the same thing with 8.
Agreed, you will need to do a fresh install of Windows, if the product key is available (usually on a sticker on the case) then you only need a copy of windows, you can re use that key (will only work on 1 machine at a time). You will need a copy of the windows installation DVD or an electronic copy on a bootable USB stick.
In the past I had switched pc's while still retaining my windows 8 install, and I just always ran driver cleaner then I installed the new drivers and voila! it worked no problems whatsoever, but you might just need to reactivate your license by going online other than that I see no reason to re install windows.