Here's the complete instructions to get the latest driver downloads for your Lenovo. Windows update doesn't always update the latest system drivers, so it's always good to go out and check the manufacturer's site.
Lenovo has a great site that is organized and allows you to get the exact drivers for your system.
By the way, the procedures used here should be used if you have a different manufacturer than Lenovo. Find the builder's site and go to their download page. Those who build their own systems regularly do this with their motherboard manufacturer's site. The individual chipsets that are on the motherboard are released through the motherboard site, not the chipset manufacturers.