insert the xp disk and boot from it.
windows setup will begin, let it.
You'll come to a screen that will ask you to press Enter to continue with XP Setup, Press R for repair, or F3 to Quit.
At his point you can either continue with setup and have it format the drive when you get to the drive selection screen or...
- Press R to get to a command prompt in the recovery console.
If youpress R it will list out all the installations of Windows it finds and ask you to select which one you want to log into. Normally theres only one listed so press 1 and enter.
When it goes to log into windows , it may or may not ask for your administrator password depending on if you have set one. Often the Admin password is the same one you use to log in every day. After entering you will be at a system prompt like this: C:\WINDOWS>
Type: format c:
exactly like that and follow the prompts. Please note that if you have multiple partitions on your harddrive then make sure you use the correct drive letter in the format command.