You need to identify the device by its manufacturer to be sure of going to the right site - many driver download sites area rip-off at best and carry risk of malware at worst.
Go into Control Panel>System>Hardware>Device Manager, find the display adapter or tye VGA device with a yellow mark beside it, then right click thta and go to Properties.
Click the Details tab, then scroll to Hardware IDs and note down the four characters after VEN for Vendor and the four which follow DEV for Device. Go to http://www.pcidatabase.com and input those details in the relevant boxes and you will see the list of all the right manufacturer's products but sadly, they aren't in order. Use Internet Explorers Edit menu then Find to type in the DEVice ID and the search will find the correct entry. Follow the link to the site for the correct driver and download it.
Some will be executable files which you simply double click to install then restart the system. Others will be in the form of a Zip file which WinZip can decomporess and show the contents, then click Install or Setup