Firmware (Android 2.3.6) XWJVZ for Samsung Galaxy S I9000
2.Open ODIN. (And close Kies, if you have it open. It is important to have ODIN open BEFORE connection the phone via USB!)
3.Select the PDA,pit,Modem,CSC file in Odin.
4.Turn the phone into the download mode by pressing and holding VolumeDown+Home+Power.
5.Connect your phone with your computer and wait until the drivers are installed.
6.When the drivers are installed, click Start.
7.The phone will be flashed and once it’s finished, it will boot up. (Do NOT disconnect the usb-cable, remove the battery or otherwise interrupt this process!)
8.You have successfully flashed your phone.
ODIN + PIT - Download Link1
I9000XWJVZ|2.3.6|OXA|November 2011|Download Link1
Root for I9000XWJVZ -> Download Link1