|You never have to buy drivers.|
There are numerous way to obtain drivers.
If this is an OEM computer, that is a branded one like Dell, HP etc, go to the manufactures web site and obtain the drivers there.
If this is a non-branded computer you need to identify your Network Interface Card and get the driver from that manufactures web Set.
A third way is to run the Windows Update and see of Microsoft Update will pick up the drivers and install them for you which they often do. This will only work if you have a legitimate and properly activated version of Windows. However, as this is a Network Interface driver you are after you are in a bit of a Catch-22 situation there.