1. Download I9000XXJVT and extract the ZIP file
3. Get your phone in download mode (Power+Volume Down+Home button)
4. Run ODIN
6. Connect your phone to USB cable. Click START button. Sit back and relax :)
This is what you should have.
Note: Good practise. Factory reset once done. This will make your phone as new coming out from factory :) Useful for ROOTING process later.