In general the "Pid" in \I386\SETUPP.INI plus the Disc Volume label
appear to be the main differentiators of many OEM vs Retail vs Upgrade disc installation processes for XP.
If you are making a custom install image to handle your systems you can often start with one edition of a disc and thereby customize the generated installation images to handle different systems / keys used in your facility. You can even make a custom "unattended" install disc or install file set for a given system that specifies the proper key for that system, installs the right drivers for that system, and installs various desired 3rd party software too -- this is able to be done by customizing a second file, WINNT.SIF.
NLITE is a tool that can help you generate customized install images, recovery discs, make slipstreamed install discs (e.g. take an XP SP1 CD and create from it an XP SP3 install CD), etc.
See the following links and various other references to SETUPP.INI, WINNT.SIF, NLITE, slipstreaming, et. al. for everything you'd want/need to know.
If the PID of the software you install matches your legitimately used key type in general I am told that you should be able to call in and activate the system without a problem, even if doing the internet based activation may not always work depending on whatever Microsoft's heuristics are.
For XP you can copy all the files in the \I386\ directory and every other directory / file under that from the CD to a hard disc or USB flash drive and just install by running \I386\SETUP.EXE
In this case, obviously the volume label of the CD is irrelevant since you're not even installing from CD. It is often much faster to install from these flash disk or hard disc copies of the installer files rather than the CD, and of course it is more convenient to use these with customized installs as well.
http://www.thetechguide.com/howto/setuppini.html
http://wiki.lunarsoft.net/wiki/Product_IDs
http://unattended.msfn.org/unattended.xp/view/web/19/
This is all pretty much standard documented commonly recommended by Microsoft stuff; it just is getting more popular for consumers instead of dedicated sysadmins to do as the need for making slipstreamed discs and customized ones with SATA drivers included etc. increases due to SP3 and the new hardware models out there etc.
Edit
http://www.tacktech.com/display.cfm?ttid=422&p=1
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