I use the dell driver pack with 7.1, but you can't upload the .cab file, nor does deploy anywhere work with nested folders.
Extract the .cab file, then you're left with a folder with folders in it (apps/audio/chipset, etc)
Then go to Driver Management in CMS, and add driver, and point it to each of those sub folders (apps/audio/chipset, etc). Make sure that you're drilling down to the x32 or x64 bit version of the driver you need. Sometimes there are even folders within those sub folders, and you need to make sure you're pointing the driver database tool to the folder with the .inf folders in it.
It is tedious, but once you get the drivers in there, you are set for that model and a lot of their lines use the same drivers. I've had pretty good luck with Optiplex 780s and a few Latitudes I've tried so far (knock on wood) and am hoping to move forward deploying a hardware independent image.