i don't know if there technically a right way to do it. but i always uninstall the old ones first. then restart, clean up my system drive of all the junk and temporary files, restart, defrag and install the new drivers.
You've got to be kidding me. That sounds like something I would say as a joke! Anyway, what exactly do you mean by "clean up my system drive" and is that necessary for just a video driver install?
what exactly do you mean by "clean up my system drive"
my computer - right click on the hard drive that windows is installed on - click properties - click on disc clean up - let it do its thing - select the carp you want to remove (i select everything but the bottom 2) - click ok.
The next batch of drivers seem to provide performance increases in a couple of Source engine games.