When you download from laptopvideo2go you should download the driver AND the inf file,which is 2 separate downloads,I usually do to My Documents.
Then double click the driver file [a black box with 7Z on it] when it asks you where to extract to make sure it is the same place [my docs].
This will create a folder with the driver number [for example 8425].
Then drag the nvdm file [the other inf download] onto the file with 8425 and it will ask you "this file already contains a file named nvdm,do you want to replace it?" click yes.
Then double click the 8425 file and almost at the bottom will be a SETUP box with 2 arrows pointing diagonally down,double click that and installation will start,follow through from there.
Sometimes you will get a box saying that this software has'nt passed windows testing,but just click continue anyway and you should be able to carry on and install the new driver from there.
It pays to read the threads for each driver on laptopvideo2go as a lot of the newest ones have problems,I use 8425 and it works well,I also read one of the threads for 8429 and a person in the thread had a I9400 and reckoned that it was all good with his machine,and I've just downloaded it to try as most of the newer ones have problems mentioned in the threads.
Thats the thing with drivers,is that you never really know what your getting until you try them,thats why its good to read the threads about each one before you download them,thats also why Dell only release drivers twice a year or so,because they test and test them for stability and make sure everything works but at the expense of performance-sometimes.
Let us know how you go.