Go into the control panel from your 'Start' menu and click on 'System'.
From there, click on 'Hardware' and select the 'Device Manager'.
In the Device Manager there should be an item in the list called 'Display Adapters'...click on it to tell you what your vid card is.
Another way is to right click on the desktop, and select 'Properties' which should open the 'Display properties' box. in that, select the 'Settings' tab and the 'Advanced'. In the box that opens you should see a tab with your vid card on it. Select it to get the details.
There are other ways, and depending on which OS you have, the ones I've described may vary a little, but you should be able to find it.