A good way to test the card is to assign an IP address to the card in the TCP/IP properties for the card in the Network Properties control panel. After you assign the card an IP address and a subnet mask, you can use the ping utility from a DOS prompt to test the card. If you get four replies when pinging, it is another very good sign that the card is functioning properly.
Using the Ping command
Step 1: Open the MS-DOS program on your computer.
Step 2: From the default location, enter the word ping, a space and then the IP address of your network card. Hit the Enter key on your keyboard.
A response of four replies indicates that the network card is properly installed and that TCP/IP is correctly bound to the card.
Another good way is looking at the card itself. If your computer is up and running and connected to a switch, hub or another computer directly with a crossover cable and the light is illuminated next to where the cable is plugged into it, then that is a good indicator of whether or not the card is working.