Just FYI, I got a legit version of XP Home Ed. On 5 different computers
But they are all mine.
If you read the EULA you can have WinXP on as many computers as you want. But one copy can only be ran at any one time, by any one cpu.
Here is the excerpt for the EULA:
1.1 Installation and use. You may install, use, access,
display and run one copy of the Software on a single computer,
such as a workstation, terminal or other device ("Workstation
Computer"). The Software may not be used by more than one
processor at any one time on any single Workstation Computer.