With your dell it is a relatively easy process.
visit dell.com and go to their support section. There you will find an option for support by product.
enter in the service tag located on the bottom of your laptop. this will narrow the drivers down substantially.
choose your wireless or wired network driver. There might be several listed, but if this is the case it is a siimple matter of trial and error. download them all if necessary.
when you download them, take note of where you are downloading to, as to have an easier time copying these files onto your usb thumbdrive.
Once they are on your usb thumbdrive, simply go to the laptop, plug it in, and run the setup file from the usb drive. No need to copy from usb onto your laptop before...