XBOX 360 Live account trouble..?

Hi, i've had my 360 for quite some time now and i've collected a fair few points from playing games over this period of time. Today i finally got a wireless adapter to access the internet and sign up to Xbox live. Every time i sign up a new profile is created and i loose all of points and games, so when i play a game it starts from the beginning and fails to find a save file. Why is this and is there anyway i can sign up to Xbox live using my current account with all my saves and points on? If so, how? Any help is appreciated, thanks. I really don't want to have to start all over again with my games for the sake of live, i just don't think it's worth it. That and i don't like the new avatar. =]