I have two Dell computers here—one running Windows 2000 and one running Windows XP. The XP machine is old and broken down, so I'm going to gut it for parts. I have the Dell-branded Windows XP installation disc that came with it, and I was wondering—can I use it to format and install XP on the Windows 2000 PC? I have the Dell drivers discs for both computers, and the XP licence key on the label stuck to the computer.
Trade In 2000 for XP
Sadly the answer to your question is "probably not." If the XP CD you have is the one that came with the PC you're breaking down for parts, it's what's called the OEM ("Original Equipment Manufacturer") Windows disc. That means that unlike the retail box version (for sale separate from the computer), the disc is probably branded by the manufacturer (in your case, Dell) and doesn't come with the fancy packaging or any manual. Here's what an OEM disk looks like next to a retail XP CD.
Even though it's not as pretty, content-wise, the OEM version of Windows isn't any different from the retail version with one notable exception. Tech site Ars Technica explains:
OEM software is tied to the motherboard it is first installed on. Unlike the retail versions of Windows which can be transferred to a new computer, OEM versions are not transferable. What about upgrading hardware? Microsoft says that anything is fair game, except the motherboard. Replacing the motherboard in a computer results in a "new personal computer," which the company considers to be synonymous with a transfer. It's not permitted with an OEM edition of Windows.
UPDATE: However, several readers in the comments say that if you're reinstalling on a PC from the same manufacturer—which you are, since they're both Dell machines—using the OEM CD with the licence key on the original case will work. I haven't tested this myself, so it's up to you to give it a try. Here's where the "probably" in "probably not" comes into play.
If it doesn't work, your only option may be to pony up for a retail copy of Windows XP in order to transform your Windows 2000 PC. Maybe Win 2k doesn't look so bad after all?
P.S. If any readers have more insight into the workings of OEM discs, or any workarounds for Trade In, who's stranded on Windows 2000 island, please let us know in the comments.