I had this issue too in my Device Manager: Base System Device
I downloaded the following driver from Intel (PRO2KXP.exe)
http://downloadfinder.intel.com/scripts-df-external/Detail_Desc.aspx?agr=&DwnldI D=4275&ProductID=879
and followed this instruction I found on another discussion board.
On LAN driver package 10.4 or earlier releases :
(1) Manually install the ioatdma.inf for the Base System Device. Extract the LAN driver package, select the Base System Device in Microsoft Windows* Device Manager and direct Windows to find ioatdma.inf in the c:\Intel 10.3\Device\PLATFORM\IOATDMA\WS03 (for IA32) or \Intel Base System Device\PLATFORM\IOATDMA\WS3XPx64 (for EM64T). This will install the ioatdma.inf.
Hope this helps you
Mac Pro 2.66Ghz, 2GB ram, 250GB, HD Dell 2405 screen Mac OS X (10.4.7)
Mac Pro 2.66Ghz, 2GB ram, 250GB, HD Dell 2405 screen Mac OS X (10.4.7)