After your PC is setup to boot from the CD-Rom first, place your Windows XP CD in try and reboot your computer.
Windows setup will begin
Hey, wait, there is no ANY key! Obviously, press a key (the SPACE bar will do).
Windows Setup will begin. Windows will display information on the bar at the bottom of your screen. If your system requires a third-party SCSI or RAID drive, you would need to insert a floppy with this drive at this point and press the F6 key. Most people who have this kind of setup will likely not need a guide on how to format their drives, so 99.9 percent of users reading this can simply do nothing and wait until Windows Setup advances
Windows setup will now load several dozen generic and standard drivers. Just wait. There's nothing for you to do here. Depending on the speed of your CD-Rom, this can take anywhere from a minute to five minutes
When Windows Setup is finished loading drivers, Windows setup will begin. Again, this could take a shot time to complete
To format your harddrive, you will act as if you are setting up Windows from scratch, so press the ENTER key to begin
Windows will ask you to agree to the End User License Agreement, just as if you were setting up Windows for the first time. Press F8 to agree
Windows will search for any existing Windows installations. If it finds a previous installation, it will alert you here. Since you do not wish to repair this install, press the ESC key
At this point, to completely wipe out your harddrive, you want to delete the existing partition. In this case, there is an existing NTFS partition that will be deleted. A harddisk can have multiple partitions. You may want to delete one or all. Many harddrives will have hidden partitions with system restore images, or unpartitioned space.
If you have a system restore partition, you are probably better off using the system restore procedure outlined by your Original Equipment Manufacturer.
If you wish to continue, use the cursor keys to select the partition, and press D to delete the parition
Windows Setup thinks you're kidding. Do you really want to delete this partition? Really, really? Windows Setup will warn you that all information will be lost. If you are absolutely certain that you backed up everything you needed, or just don't care about the exisiting data, then press L to continue
Your partition is now completely wiped out. It is not partitioned or formatted. Windows wants to know if you would like to install Windows now. If so, follow the prompts...Windows Setup will create a new partiion, format it, and install the operating system