Hola d2jsp members 
, that guide is about format your computer and setup Windows XP.
!!! Attention !!!
REFORMATING WILL DELETE ALL FILES FROM YOUR COMPUTER.
If there are any files you want to keep, make a backup on a extern hard drive or on a CD .
What you will need to format your computer:- A Windows XP installation CD with a valid Product Key
- A computer which you want to format/install Windows XP
- If you are getting internet via USB, you will have to plug off the USB,
before formatting and plug it on after the computer has been setted up
Step 1: Booting from CD
Start your computer, put in your Windows XP installation CD and shut it down.
Boot your computer again.
A message will appear equal this: Code
Press f12 to boot from CD
Press "F12" and boot from CD. ( It's important because we are gonna delete C: )
Step 2: Deleting Partitions
After you booted from your CD, a message like this should be shown: Code
Setup will now inspect your computer hardware and configuration.
After you booted from your CD, you will get to a " Welcome to Setup page".
Press Enter, press F8 to accept the Windows XP lincensing Agreement.
Then you can decide, if you repair your existing Windows XP 
Press ESC.
Install a fresh copy.
Your screen will be now, a blue background and in the upper left corner should be written Code
Windows Setup
Wait some seconds and you should be in a "Welcome to Setup" menu.
Press "ENTER" to start the installation.
Now it shows up the Windows XP License agreement.
Read it, and press "F8" to continue.
You're in a partition menu:
Select the partitions, you want to delete ( If you just want to reinstall Windows, choose C: ).
Press "D" to delete the selected partition.
It will tell you:
Code
The partition you tried to delete is a system partition. ( etc... )
Press Enter to continue
It will show:
Code
You asked Setup to delete the partition
Press "L" to confirm and delete the partition.
Now, you have to select, where to install Windows XP.
Press "ENTER" to confirm the partition you've choosen and install Windows XP into.
After that, you need to format the hard drive, NTFS is recommended, select it by using the arrows and press "ENTER".
The harddrive will now format, copy files and initializes the Windows XP configuration.
Press "ENTER" for restarting Windows XP ( It will do it itself in 15 seconds )
While rebooting, Windows XP CD has to be in the drive.
DO NOT PRESS ANY KEYS WHILE BOOTING
Step 3: Install Process
You're coming into the install process, which contains 5 Steps:- Collecting information
- Dynamic Update
- Preparing installation
- Installing Windows
- Finalizing installation
Regional and Language Settings
First step where you have to do something, will be the "Regional and Language Options"
Click on "Customize".
Select:- your "Default input language"
- Installed Services ( Keyboard.. )
Press "OK"
Press "Next"
Windows XP Professional Setup
Add your Name/Organisation ( You can leave Organisation field blank )
Press "Next"
Now it is time for your product key.
The product key will be on the packaging that XP was supplied with.
It is 25 digits long.
Some OEM computers will have a sticker on the side or back with your product key.
Input the key.
Press "Next"
Select:- Computer name (optional)
- Administrator password
- Confirm password
Press "Next"
Setup your Date and Time Settings.
Press "Next"
Your windows will continue installing.
If a network card has been detected, you will get into a "Networking Settings" menu.
Select "Typical settings"
Press "Next"
Workgroup or Computer Domain
Select:
Code
No, this computer is not on a network, or is on a network without domain.
Make this computer a member of the following workgroup: WORKGROUPD
Windows XP will continue installing, and will restart automaticly.
DO NOT PRESS ANY KEYS WHILE BOOTING
Windows will adjust your resolution.
Press "OK"
Internet Connection
Now you have to setup your internet connection.
If your computer connects to a home network or directly using the network card. select "Yes", otherwise "No".
Activate Windows option appears next, we recommend that you select "No, remind me every few days", that will allow you to make sure everything is correct and running OK before you use up one of your activate attempts.
It also allows you to setup your security options and internet connection correctly.
Press "Next"
Windows XP says "Thank you"
Press "Finish"
Now setup the Users, which are using this computer.
Press "Next"
You have successfully formated/installed Windows XP!! 