Is it a pre-configured computer that came with the network card already in it? Such as an Asus, HP, Compaq, etc...

If so just goto their website, find the support site, find your computer model number (There should be a sticker somewhere on the computer with the model number) and find your drivers.

If the network card was an addition, and you don't have the model number, you may have better luck than me, but like I recommended before, its only $20 for a new one...