Most cards have a 10/100 light on the abck. If the light is off it is at 10, if it is on it is at 100. You might also try downloading full drivers from the venodr. many of these have monitoring utilites that will show you your current connection speed. the other thing you can try (if the network card does not have a 10/100 light) is to just plug it into a switch/hub and see on the switch/hub if it lights up as 10/100. Unless you change the NIC, it should default to auto-sense.