Another option is to download drivers from the Microsoft Update Catalog:http://catalog.update.microsoft.com/v7/site
In my case, the packages from nVidia would only install the HD Audio driver for the HDMI output, but not for my graphics card (9300M), but the latest driver from the Update Catalog worked fine. So if you're having trouble with getting drivers to install, it's worth a shot to check there.
Note: the Catalog has a ton of different drivers, so be sure to check you get the one for x64 before you download. Click on the driver name for an info popup.