Every Dell computer purchased with Windows XP already installed also comes with an operating system reinstallation CD. The CD includes all Microsoft Windows XP service packs that were part of the original installation.
Your Dell computer has a service tag on the back, with a five- or seven-digit code containing a sequence of letters and numbers. This code is assigned by Dell and identifies your particular machine.
If your Dell Windows XP computer develops problems, restoring your system to a time before the problem existed may be enough to fix your Windows XP installation.
From the Start menu, go to "Accessories/System Tools/System Restore" and choose a restore point.
After restoring the system, reboot and run the program(s) again that were experiencing trouble before.
If System Restore didn't work, some models of Dell Dimension and Inspiron computers come with a software application called PC Restore, which will reset your operating system to the way it was when it left the factory.
If neither of the above methods solves the problem, you will need to reinstall Windows XP.
Back up everything you think you might need later on to a CD, DVD, flash drive, an e-mail to yourself or another machine networked to yours.
Put your operating system reinstallation CD into the CD/DVD drive. If you have two or more CD drives, make certain you put the CD into the drive that comes first electrically. This is the drive whose letter comes first in the alphabet, unless your drive letters have already been reassigned. If they have, reinstalling XP will reset your drive letter assignments back to the default.
Turn your computer off and reboot from the CD.
You will see a screen with the beginning of the Microsoft Windows XP EULA. Step through the screens and accept the agreement.
Next, you will be offered the chance to reformat your hard drive and remove all partitions. This provides a clean installation and is the best option for most users. You may also be given the choice of a FAT or NTFS file system. NTFS is the best choice for large modern hard drives.
Continue to reinstall the operating system, following the prompts.
Connect to the Internet and visit http://www.update.microsoft.com for service packs and critical updates. Keep doing this until the site tells you there is nothing else to download and install.
Dell Solution Center, listed on the Start menu, will take you to the Dell website at http://www.dell.com. Here, you can get any new or updated drivers for your system.