Sessions

Hello People, I wanted to have your assistance in deciding few things here, basically I want to auto populate a registration form for people visiting second time or so on. I have already started a session,I know that session is a cookie so is it better to rely upon the session cookie for auto populating or create another cookie on client side. If i am not mistaken ini_set('session.gc_maxlifetime', 3600); increases the time session cookie expiration time to 1 hr right. Please give me ur suggestions on this. if some one has a working code can you please share? Thanks, V