Here is a guide to root the Samsung Galaxy S 4G within five minutes. First you need to download superoneclick from the links given below. Unzip it and move the contents to a folder on desktop. Then, enable USB debugging mode on your Galaxy S 4G. Do this by going to Settings.
Then, connect your Galaxy S 4G to the your computer. Make sure you do not mount the SD card. Otherwise, you would not be able to root the phone. Now, start Superoneclick.exe and select rageagainstthecage under the exploits.
Click on the root’s tab and wait for few seconds for the process to complete. Reboot your ‘rooted’ Galaxy S 4G. Download any root checker app from the market to check if your device was successfully rooted or not.
Also check out – ADB Windows Setup