Dell does not have the proper DOS drivers that will work with Ghost.
You have to pull them from Broadcom and then setup a new NDIS NIC in the boot uitlity.
http://www.broadcom.com/support/ethernet_nic/netxtreme_desktop.phpScroll down and grab the DOS NDIS2 drivers, unzip them on the disk some where and use the Ghost Boot Utility to define a new NIC Driver. You just have to point to the B57.dos file and you are all set.
This worked for our XT's on the Ghostcast server.