Hello tonychanmbers,
According to the End User Licensing Agreement (EULA), your proposed method is the only Microsoft-approved method for transfering an OEM license for Windows XP.......hand-in-glove with the computer on which it came first installed.
If your old employer happened to have installed other Microsoft software and/or operating systems acquired under Volume Licensing Agreements onto these computers, it would be best to sell the computers with their hard disk drives wiped. That way the eventual end users who purchase the computers are not misled into thinking that the sale of the computer includes more software than the computer is licensed for.
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