Most of us use internet at internet cafes and yes, most of us like to use gtalk. But everyone is afraid of being tracked or traced when their usename is being known by those whom they don't wish to know. So, here is the tip of removing the trace of your username.
Everybody does the same thing like deleting the username and password and typing stupid things and login again to hide their username and password. But that's not enough. Your username and password can be retreived from the registry editor.
Here is the key.
HKEY_CURRENT_USER\\\\Software\\\\Google\\\\Google Talk\\\\Accounts
Here, you'll see the last logged in usernames. If there is your account you can delete the subkey.

Well, this is only a fraction of infromation that I know from my friend. If I've made any mistakes, please correct me.

P.S sry for grammatical errors

thz...bro....