Oberon,
There are no genuine "multiple installation" licenses for XP sold thru retail channels to indivdual consumers. OEM licenses and retail licenses are valid on one device only. If you have more than one computer, you need an individual license for XP for each computer.
Please follow these steps for assistance:
Step 1 is to run the utility at this link http://go.microsoft.com/fwlink/?linkid=52012, then click the Windows tab, click the "Copy" button, then paste the report into a response in this thread.
Step 2 is to look on the computer or with the materials you received with the computer or with your retail purchase of Windows to see if you have a Certificate of Authenticity (COA). If you have one, tell us about the COA. Tell us:
1. What edition of Windows XP is it for, Home, Pro, or Media Center, or another version of Windows?
2. Does it read "OEM Software" or "OEM Product" in black lettering?
3. Or, does it have the computer manufacturer's name in black lettering?
4. DO NOT post the Product Key.
Not sure what to look for? See this page for reference: http://www.microsoft.com/resources/howtotell/en/coa.mspx
