MSN Add-in windows Messenger

I have both versions of MSN. The one is MSN 5 and
the other is the more recent version 6.1. I would like to
get rid of the version 5 but don't know how. Both of them
seem to compete. One will come up and say " click here"
you have signed on at another location or it will say I
have clicked on another "computer". All very confusing
and annoying. I also get so much feedback that I am
unable to carry on a real conversion on Audio. Can you
tell me why? Thanks