>>> My friend came over and decided that I needed instant messanger, yahoo and installed Mozilla, I already had Avast, now I am confused.
Sounds like your friend gave you 4 different software applications that do different things, and you are concerned that things are now redundant?
Instant messenger is a chat program.
Yahoo has a bunch of different stuff out there, but sounds like you are talking about the Yahoo toolbar.
Mozilla is a web brouser... a competitor of internet explorer... without all the security flaws... KEEP THAT!
Avast is an anti virus application... unless they also have a browser too.
I recommend that you explore each application, play with it, see what it does, and if you don’t like it, go to “My Computer” and uninstall it.
Mozilla is a keeper though... don’t use IE (internet explorer) unless you have to... just my opinion.