old xp disk on new PC

You can install it but you'll have to call Microsoft to activate. If they asked why, just tell them you've had to replace some components, e.g., hdd, RAM, and sound card. As long as you're running on only once computer you're fine. Done this any number of times and never a problem and no one ever gave me a hard time.

The license for XP only allows you to run it on one computer at a time, which means legally you'd have to remove it from your old computer. Of course when asked you could tell them you were only running it on one machine even if it were installed on more than one but I don't know if this would affect your ability to get updates. While you can run pirated copies of Windows on a machine as often as not you cannot do updates. I don't have a clue how Microsoft knows when you're running "Genuine" Windows and how running a copy on 2 or more machines affects updates. You could try running it on 2 machines and see what happens but I want Bill to know I'm not advocating this, don't want him taking my house

If the board "dies" and needs to be replaced, you can use the one you have