Gnutella Forums - playing: asf, avi & wmv files

i received my imac from a family friend who moved away so all of the software on it was his. so i am still getting used to it all. my question though is for videos how do i view asf, avi & wmv files? if i click launch the only thing that happens is that sand-clock comes up showing that it is opening and then nothing happens. i am guessing that in order to be able to play these files i need specific players used outside of limewire in order for the files to work. i was also wondering if i could open my mp3 files with a different and better player. if these players are free please give me links to them and a step-by-step analysis as to how to play the files. example: do i need to be out of limewire in my shared folder to be able to play these files? thank you