A quick search would have provided an answer quickly. HERE is how you can create an OS disc if you were not provided one. You also have a utility on the hard drive, called PC Restore by Symantec, for completely reinstalling the original hard drive image. Follow these instructions:
1. Power the computer on.
2. When the Dell screen appears press and hold the Ctrl key on the keyboard, press the F11 key, then release them both at the same time.
The Dell PC Restore by Symantec window appears.

NOTE: Only press the keys one time; if you press them more than once you will receive a keyboard error and will have to start the process over.

3. Click the Restore button. A caution message appears advising that all data will be lost.
4. Click the Confirm button. The progress window appears. When the restore is complete the message "The system recovery process was successful" appears.
5. Click the Finish button. The computer will restart.

Trouble is this poster is not missing the Dell cd. Contact the manufacturer of the other PC for a possible solution. You might not be able to use the Dell's cd, but you can try booting to it to see if it works. Dell cd's are supposedly tied to the Dell bios.

Sorry, I've seen the question so often it's a kneejerk reaction (I used a macro reply). Of course, the forum is open to anyone, even if you have a non-Dell question.

dont_have_a_clue_about_computers,

If you can install XP from your Dell CD (which I doubt) you can change the Product ID to the one shown on the sticker on the case of the non-Dell system using the steps here before activating. If you can't install from that CD, the process should work after you install XP from a non-Dell CD if you can borrow one from a friend.

You need to get the XP disk from manufacturer.

You cannot use regular OEM cd because all XP cdkeys written on the sticker that is attached on the PC case cannot be activated.

i have tried using an oem XP disk and it wouldn't work. my xp upgrade disk was murderedso i couldn't use but then i had an idea. i put in my xp upgrade disk and when it starts to intall take the upgrade disk and use the OEM cd from my 5100 laptop to finish the install and when it restarts just pop the original upgrade disc to finish the install.