Are you Updating from an earlier version of Windows?
If so, are you planning on retaining existing information?
Be careful if you are, as the incorrect procedure may see your Hard Drive overwritten, and earlier information lost forever.
If you are "Repairing XP" there is a procedure for doing that, ("Repair XP" will retain all existing Data), and the option will show up when you insert the WinXP CD, if you already use WinXP in that PC.
Place the WinXP CD into the CD or CD/DVD Drive, close the tray.
The instructions will come right onto the Monitor screen in front of you.
Follow the Instructions.
WinXP installs almost every driver you should ever need, ensure you get all the Updates direct from the Update Site, there's around 170MB now.
There are many times during the update/s, where you are advised to re-start the PC.
I repeat: Follow the on-screen instructions at all times.
Ensure you register your copy of WinXP, or you won't be able to update, because of the WGA File (Windows Guaranteed Advantage) which is no advantage to you, but is to M$oft.
If you run into trouble, call back here, with for further advice.
Kind Regards....
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"The number of inventions increases faster than the need for them at the time" - SparkY