You need to look elsewhere for the problem if you are discussing Dell computers delivered with Windows pre-installed.  Dell uses a volume key to install the operating system which almost never matches the COA sticker affixed to the computer case.  Further, Dell supplied OEM Windows reinstallation disks are pre-activated on the Dell computers that are delivered with them, so no key is required for installation.  The only case in which a key should be necessary is for installation of a commercially purchased version of the operating system, and that key would be found with the package that enclosed the disk.  
I have encountered several Dell computers with the wrong Windows (25 character) official key. One stopped admitting users, and would login only briefly.  Another would not allow Windows update. Now, I have encountered another two computers yesterday, so I would like to correct the registry  to use the correct key, before such problems begin. However, the standard techniques have not worked for me.  I have had to remove the Windows folder and reinstall XP.  What else works? -- avid0g
computer using wrong windows key (found on chassis)