Buying used OS

[CRTGAMER]

My version on fresh installs did not need activation. I made a slipstream version with the service packs preinstalled from the original disk and service pack downloads. I guess I'm lucky my OEM doesn't need that silly activation, or maybe the service packs?

http://labmice.techtarget.com/FAQ/winxpfaq.htm

The product activation feature of Windows XP (and Office XP) is designed to discourage casual copying of the software. Once you load Windows XP and type in the Registration Code, it creates a unique ID for your workstation based on your system configuration and prompts you to register that ID with Microsoft within 120 days, or your Operating System will no longer function. Although the process only takes a few moments to complete over the web (and slightly longer over the phone), this requirement has caused a storm of controversy. ( For more information, see Microsoft's Product Activation FAQ) Product Activation is only required on the retail and some OEM versions of Windows XP and not on the volume licensing program that most businesses use. Windows XP upgrade licenses acquired through one of Microsoft©s volume licensing agreements, such as Microsoft Open License, Enterprise Agreement, or Select License, will not require activation. Installations of Windows XP made using volume licensing media and volume license product keys (VLKs) will have no activation, hardware checking, or limitations on installation or imaging.