You're probably going to need more than the OEM XP disk.
Dell shipped separate disks for the operating system, chipset and device drivers, fax/modem, soundcard, and system software.
Check - http://support.dell.com/ Under Dimension and then 4600.
They've got a very thorough description of what they call the Windows XP reinstall. It's actually a reformat/installation. Spells out the disks needed and the order in which things need to be loaded. They do have some downloads available for drivers.
Good luck