I use winamp as well on a pc.
Its the fastest in regards to managing mammoth amounts of files.
some skins are amazing, the web tv and web radio are ok but some content is quite rude.
I Tunes has a preference to allow it to manage your music in the settings.
You should deactivate that or you will end up with a hard drive with two music folders and double the content of the same thing, extra folders for each artist and album.
If I tunes has doen this to your music, just search that folder only for *.mp3 etc. and this will alloe you to grab them all out of the folders at once to another folder.
If that feature is off and you have established music file setup and a file sharing connection between your mac and pc,
I tunes will happily play it over the network without taking a copy and stuffing the file.
btw "its what you<-- did to your computer"
if you upgraded from a very early version without studying new features, there at least should be a sign in the program saying wait! if your new to this version etc. catching the silly mistake.