You have an intel based ethernet device.  You can find the dell approved drivers here:  http://ftp.us.dell.com/network/R159293.EXE

You can get more recent drivers at intel.com: http://downloadcenter.intel.com/Detail_Desc.aspx?ProductID=879&DwnldID=4275&lang=eng

For these drivers to work, you must first install the chipset drivers.  The dell approved drivers are here:  http://ftp.us.dell.com/chipset/R158363.exe

You may also be able to find more recent chipset drivers at intel.com