If you want to delete everything on the drive, and start fresh, backup all of the data you want to save, pictures,txt files,movies,downloaded applications, and save it either on dvd, or if you have one, or can get one, and external hard drive. After that is done, and you better be sure you want to do this, because recovering is very difficult after this is done. Boot the windows xp install media, and when it asks where you want to install the OS to. Go to advanced, and then delete the partition, or both of them, if you want to erase D: also. Then either create a partition for C: and leave space to create a D: partition after windows is installed, or just let windows choose the size of the drive, it will create a single drive of the largest partition it can. Then you can have the fun of installing all of your drivers and programs, and recovering your saved data, setting up email, and network again.