ummm...
install the software onto your working computer, then use the
guest hack
then turn off auto sync, then plug in your zune
then copy all the stuff onto your zune to your computer by dragging all the songs onto the sync list
there should be a button that says copy from device... or something like that.
after everything is copied you'll have all your songs on your computer, and on your zune.
you might get a problem with a pop up when you plug your zune in with the guest hack on. just close that and don't worry about it untill all your music is on your computer.
rename your zune and set it up as the home computer after you get all your music.
you can turn autosnc back on after you music os copied too.