You're under-performing your GPU if you use those older drivers in comparison to the newer ones, especially using the dell ones, it's really senseless to me someone using the 84.69 drivers (no offense). The reason you can't install the drivers from the nvidia site is because the INF included in those drivers don't include laptop GPU's, so when you try to install it says your hardware isn't compatable. In reality it is compatable, but nvidia doesn't want to support notebook drivers, they want the manufacturers to supply them. But then the manufacturers don't keep up and you're left with underperforming hardware. Get it?
So what laptopvideo2go does is modify those INF's, making the drivers compatable with laptop GPU's, so you won't get that error message when you try to install and it installs. The drivers you download from that site are the exact ones from the nvidia site, except you're putting the modded INF in the install folder so it allows you to install it.
It's pretty easy, you just download the driver and its modded INF from the site, extract the contents of the driver into a folder, take the modded INF and put it in the folder (it should then ask if you want to replace the INF file, say yes), and that's it. Just then uninstall your current driver and then click on the setup file in the driver folder.
Sorry for the long explanation, but I really hate to see someone handicapping their hardware because they're not knowledged about the subject.