You don't need to install any samsung anything.
Settings -> About Phone -> USB Settings: Ensure "Ask on connection" is selected.
Plug in USB cable, connect to PC.
Select "Mass storage" on the menu. Your device is now connected and charging, but you don't have access to the data yet.
Now drag down the notification bar from the top of the screen. It says "Ongoing: USB connected. Select to copy files to/from your computer". Press that. Press "Mount".
Your Internal SD and external SD now mount on your PC and appear as drives.
Edit: If that doesn't work for you then there's something wrong. I haven't installed Kies on any machine I've connected the SGS to. It may be that you require Admin rights to install the usb drivers that are sent over as the device attempts to mount (not sure).