Well, the most common hardware that requires drivers are Video card, Sound card (most of the time is integrated on the motherboard, so you have to know which one do you have) and network card.
I would suggest searching for the disc (if you have it) or go to the manufactures website of your motherboard and videocard, sometimes they have utilities to let you know which one you have.
EDIT: I found this program on a disc I have, but it does the trick. Its called
DriverGenius
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