ive used limewire since 2002 and never gotten a virus.
you just have to be smart about the file sizes of what your downloading. if it seems to large or to small odds are its something you dont want on your computer. if it seems to fall in the typical mp3 file size range, download the hell out of it.
however i can guarantee you you not gonna find that song on limewire. all youll get is about 10 thousand porn downloads.