At work I have several older computers running windows xp and several Windows XP cds. The problem is I don’t know which CD goes with which PC. I want to do a repair but if the wrong cd is inserted then the repair halts.
Is there any way to find the correct cd?
The wrong CD or the wrong code?
To identify which version of XP each computer has, right click on your “My PC” (or similarly named) icon on the desktop; the OS is listed on the first tab. You should be able to use the correct version on any given computer; if you can’t, that means what you have isn’t exactly a “Windows XP” CD, more like a “Windows plus whatever the PC’s manufacturer loaded here” CD, so the manufacturer info on the CD should be enough to identify which computer it belongs to.
At some point the CD will ask for a code which should be on a sticker on the PC itself.
Certain XP CDs only accept license codes from their own brand PCs. I’m thinking of Dell and HP, but there may be others. Similarly, a generic XP CD may well reject license codes from Dell or HP machines.
Note though that IME a Dell CD will work with any Dell code.
That said, you may well be hitting a different issue: that of the XP CDs not being the same service pack level as the installed OS. To counter this, you will need to obtain or create a bootable XP CD with the latest service pack slipstreamed.
I used to use nlite for this.
Download and run this free keyfinder program http://www.magicaljellybean.com/keyfinder/
This will give you the key to each installed program, if you still have the origional CD covers you can match the Key to the individual computer.
Or open each CD and you will find Windows CD key in one of the following locations:-
I386 Folder/ WINNT.SFI (Open this file with notepad and you will see all the unattended information with CD Key in it)
Find any Last Session.ini file and open it with notepad and you will find the CD product Key.
I386 Folder/ UNATTENDED.txt
Note: Not all setup contain these files 
Again you can match the individual Installation CD to the computer.
Also note there is OEM install CD (Original Equipment Manufacturer)and Volume License XP. If you have a CD from the manufacturer, odds are it’s OEM. An OEM code will not be valid for VLK or vice versa. Then there’s upgrade installs with their own key, IIRC. Also there’s XP and XP Pro - the latter allows you to logon to domains (bigger business, again) while the former was home use only since it only did workgroups.
Volume License typically is only relevant for larger companies that bought several copies of XP to install on existing computers.
There are different “groups” or “kinds” of XP install CDs as others have pointed out, but no one XP CD has one specific key sequence hard-coded onto it. The install CDs that are of the same type will be bit for bit identical. They each contain the same key algorithm which can recognize & validate millions of different valid key sequences out of the roughly 10 quintillion combinations possible with a sequence of 25 places, each containing 36 different possible characters (26 letters & 10 numbers.) I think (36[sup]25[/sup]=10,314,369,046,585,278,464 give or take.) Probably don’t use the O’s or I’s or zeros or ones. Bad enough they used B’s and eights! Got that wrong a lot…
OK, but if the OP wants to do a repair the original CD surly has to match the the installation.
With the Jellybean keyfinder he can if necessary change the key to match the CD.
