The version of WinPE used in Ghost is the 32 bit, so you need 32 bit Vista drivers. It is adviseable to include drivers for both the NIC and the SATA chipsets on your machine, as WinPE 2 only has basic SATA capability and a lot of new SATA chipsets have been released since it first shipped.
Basically, check from the WinPE command prompt that you have a valid IP address. If not, then its a good indication that the wrong drivers are being used.