I have Windows 7, 64-bit and an 82579LM, so I installed the latest 18.5 software package to see what would happen. I only had the base drivers installed, but after running the executable, I got the extra tabs including the VLAN tab. So I'm not sure what's happening to you, but I have a couple of thoughts that might help.
Make sure you use the latest installation package from: http://downloadcenter.intel.com/Detail_Desc.aspx?DwnldID=18713. The driver version is the same you have, but the PROSet version and ANS driver versions might be different if you are using an older version of the software package.
Since you are having trouble with the installs, I would completely uninstall the software from the control panel. And when you install the new package, you might want to right-click and use the "Run as administrator" option. That might not make any difference, but at least you can rule out any permission issues for your user.
I hope this helps.
Mark H