. You can install your copy of XP as many times as you like, however possibly depending on the version, you can have it installed on multiple machines as well. All you have to do is call the Customer Service line (which is open 24/7) and tell them that you have changed hardware or building a new PC
DON'T do that. If you ever need to re-install, or if you change enough hardware in that first system, it will need to re-activate. At this point you'll be screwed, MS won't re-activate it, as you've told them you took your copy of XP off this machine.
Also, there seems to be some confusion in this thread as to what the difference between XP Home
is. Let me run over the biggest differences:
Dual CPU support (Home still supports hyperthreading fully).
Advanced Directory services
Simultanious File sharing for more than 5 computers
Remote desktop control
If you don't know what any of the features are, then you definately won't need them. Basically if you're not running a dual-cpu workstation or in an office with 50+ other computers, then Home is the windows you want.
Full feature comparison is here:http://www.microsoft.com/windowsxp/pro/howtobuy/choosing2.mspx