Well, I guess the word 'rebuild' is synonymous with 'reimage' or 'reformat' in some parlances...
Anyway - is your computer a 'plain box' computer or branded (e.g., HP, Lenovo, ASUS...) computer? However, the steps are basically:
1. Backup your data
2. Reboot computer and insert your recovery CD/DVD-ROM or Windows install disc
3. Go into the BIOS (generally by pressing the delete button - check the screen)
4. Look around for 'boot device priority' and ensure your DVD drive is set above the hard disc
5. Save and exit
6. Boot into the CD/DVD-ROM
7. Follow the instructions
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For fresh install of XP only (not recovery CDs - as they generally do it automatically)
8. Locate driver discs that were probably provided with computer
9. After XP install, put the motherboard [ASUS, Gigabyte..] disc into the CD and follow the instructions to install critical drivers.