Step-By-Step Process of upgrading your Samsung Galaxy S Mobile to Froyo 2.2 in India:

Launch Kies Software from your PC and connect your Samsung Galaxy S Mobile in "Samsung Kies" USB Connect  Mode. To make it as default : Settings > Wireless and Network > USB Settings > Samsung Kies - Enable

Click on "Firmware Upgrade" icon (second icon from right in the icon bar). Mostly, automatically, your Firmware Upgrade Available Window pops-up as soon as you connect your Mobile in Kies.

Though your contacts, installed apps, pics, videos, files, messages, all other stuffs remains untouched by this upgrade process, it is better to take backup of those to you PC, as a just-in-case precaution.

need to ensure that internet connection is available before you agree and proceed next

its better to save your data in server, also for a just-in-case scenario

Download of the binary files start. Ensure that your mobile phone is never dis-connected during the whole process. If its a slow connection, it take quite a while to download. for my 256Kbps, it took almost 30mins..

Once downloaded, upgrade process starts automatically. You can see the Android Work-in-Progress logo on your Mobile Screen now and the blue progress bar of downloading the new OS to your mobile.

Once the upgrade is complete, your Samsung Galaxy S Mobile reboots. you can see the reboot code lines in green during the first boot. Also, it takes a little while, almost 2 mins in my case, for the first boot.

You can verify that your OS now is Froyo 2.2 by  navigating to
  "Settings > About Phone"
 Model Number : GT-I9000
 Firmware Version : 2.2
 Baseband version: I9000DDJP2
 Kernel version: 2.6.32.9
 and most importantly..
 Build Number:  FROYO.DDJP6


Overall, its good to be more nearer to the latest Android OS available. :)