Hello and welcome to Tom's Hardware Forums.

Ignore the last post - some confusion there, I think.

If you know or can see the make and model of your motherboard, Google for it and go to the manufacturer's website. If not, go into Control Panel>System>Hardware>Device Manager and look for yellow marks. If there are none, everything is working properly but if there are, pick one and right click the entry and go to Properties. Click the Details tab and scroll to HardwareIDs then note the four characters which follow VEN for Vendor and the four after DEV for Device.

Go to http://www.pcidatabase.com and enter those details into the boxes and you should be led to the right place for the correct driver.