hi,

now that i m finally connected (thanks to very helpful people on this forum) ... how do i launch programs as soon as i am connected?

Well, I suppose you could modify the scripts you use to start the connection, or better yet create another script that starts the connection and then starts whichever programs you want.

If you are using kppp there is the Setup -> Accounts tab -> Edit -> Execute tab.

i am on gnome ...

Let's assume that you have a directory called /etc/ppp. In that directory, you should have several scripts, including one called ip-up. If you read that script, you will see that ip-up will look for a script called ip-up.local, and run it if it exists and is executable. If you do not have ip-up.local, create it and add the command lines (one per line) for the apps you want to start when you make your internet connection.
Something like:

#!/bin/sh
/opt/mozilla/mozilla

which would be executed by ip-up to start mozilla when the connection is made.