To image your client PC, it is first booted to WinPE (the PreOS). At this point, the WinPE operating system has control over your hardware, and the operating system installed on the local hard disk is not running.
It is WinPE (based on Vista 32 bit) that requires the network card driver, as it also needs to be able to communicate with the Ghost server in order to transfer the image it is creating.
The easiest way to find the appropriate driver is to go to the website of your hardware supplier, find the downloads for the model of PC you have, and download the Vista 32 bit drivers for the LAN chip in your PC.
Then add those drivers to the WinPE environment that GSS creates.