I am trying to free up some space...and noticed that
c:\Program Files\NVidia\Installer 2 is pretty large.
Is it safe to dispose of it?
I suspect it will be safe, but cannot be absolutely sure. If you can, I recommend making a compressed file containing a copy of those folders, putting that on a backup media somewhere, and deleting them.
Windows MAY throw a warning saying something like "deleting these folders may cause registered programs to not work", which means they are specified in the Registry as being important to the program (nVidia control panel). This may or may not be a valid warning, since sometimes installers specify things as important that really aren't. My suspicion is that that directory is there incase you select "Repair" in the Programs and Features control panel.