If you don't also have the companion drivers disc, then you'll want to go to the Dell support site and download those and put them on a separate CD or flash drive. I would also recommend getting the "Network Professional" version of the SP2 and SP3 installers and having those with the drivers.
Then you pop the XP disc in the drive, boot from it, follow the on screen instructions. Along the way you will be asked alter the partitions on the drive, say yes, delete and recreate the partition so you'll be given the option to format the drive. Once you have XP up and running, start installing the service packs if you downloaded them. That way you can be up to at least SP3 before ever connecting to the Internet. Then you can start installing drivers, and finally you want to install all the latest security updates. After all that you can concern yourself with the installing of programs and whatever else.