There are the OEM, the Retail and maybe a few more. Sadly you can't be sure about this unless you try it.
A friend of mine has a very old HP desktop system that supports a max of 256MB of RAM and has an 8GB hard drive. It originally came with Windows 98 but he had upgraded to XP Home at some point. The system is now having hardware problems and not worth fixing.
I have an old Dell desktop that I want to give him and that is still much better than his old one. I'd like to format the drive, install XP, then transfer his data from the old system to the "new" system. Unfortunately, he can't find his XP disk but we do have his license key.
Can I use any XP Home disk to install and just enter his license key at the prompt?