First, go to Windows explorer and investigate the driver disc that came with the card. You will probably find something like Drivers; Winxx or something similar. The point is, you need to know where the drivers are located on the CD.
Armed with this information, go to Control Panel; Add New Hardware and select; "No, I want to select the new hardware from a list". Click on "Network Adaptors" and "Have disc". Now follow the wizard, making sure you point to the drivers (use Browse) determined in the first step above.