Try looking in device manager. You may see a couple of yellow question marks. If not then it may be that the cards are not compatible with vista then again with some cards you have to put the software on first before it will be seen...Mind you, if your not sure on the manufacturer then this is going to be difficult..maybe...
If you do see the question marks then you could right-click on them and choose update driver. It may find one for the card but it's doubtful.
If the above is proving fruitless, pull the cards out and have a real good look over the card. You might be lucky and spot a name..