Well, that same folder can be used to replace your current PC's library. The only difference is that the PC keeps the iTunes folder in My Music by default whereas the Mac keeps it in Music. The good news is that the folder works just as well on either platform.
However, this method
replaces the current library. If you just want to
add these songs to your PC's current library then drag the iTunes folder you just saved to the open iTunes (app) window to import.
There's a better explanation of backing up libraries (using iPods)
here by the way. Apple puts it far more succinctly than me.