Check your disk for scratches, or fingerprints. Clean your cdrom or dvd drive with compressed air. Try an external cd drive.
Are you using the Dell xp disk that came with your computer? A replacement disk can be ordered from dell for about 7.00 and shipping.
Your computer has a recovery partition. It can restore your computer to factory condition. It will usually destroy anything you have added since it was new but there may be options that can help you backup your data, music and files. Read the info on the linked page:http://support.dell.com/support/topics/glo...;l=en&s=dhs
If you don't have your files backed up we can help you with alternative methods of saving your data but your will have to reinstall any programs you have added since buying the computer.
For more information re your computer, start at the dell support home page and enter the service tag from the back of your computer.http://support.dell.com/support/index.aspx...;l=en&s=dhs