What is the instalation directory?
That number reflect all the files on the folder and subfolder of the instaltion.
I've once instaled a program by mistake under "C:\program files\" instead of the normal "programfiles\programname"
under the uninstall the size was the total size of my program files folder and it's subfolders (all others programs) so I got some ridiculous reading like that.
So that could be the case.
"Chile is a thin and tall country"
either way... fuck that.
Download the latest driver, shitcan that one, and install the new one.
Backup your system first if your paranoid about it.
thanks to Silverwmoon!