RE: I cant install Ethernet controller and wifi
If you didn't receive a drivers or resource CD / DVD with your system them unfortunately the best way to get the drivers is to download them to another system and copy them over using a USB drive or something similar.
Here is a link to the downloads page for the Latitude E6430. It defaulted to Windows 7 64-bit version for me but make sure you check the operating system filter on the downloads page when you pull it up to make sure. To help me better troubleshoot this issue please right click on my Dell Todd username and send me a private message with the Dell Service Tag of your Latitude E6430. Please keep all troubleshooting discussions here on this public thread so that others can see what we discuss.