I recently got a new PC, shocking as it is, when I attempted to sync the phone to the new PC, it is asking me if I want to delete everything on my phone to match the iTune (which is currently empty), and I couldn't find a way for iTune to sync to match my iPhone, anyone know how?
You can only match your phone to your library, not the other way around.
I've also struggled with this, but there is no way export the library on your phone.
What you should have done is made a back-up of your iTunes library, opened iTunes while holding Shift, then select that library to import it.
That way you would have had the same library, and your phone would have synched to it.
(Thank you Captain Hindsight!)
All I did was copy the iTunes folder from My Music on my computer. Unless you want to save playlists, really the only thing you need is the actual iTunes Media folder that houses all the songs. If you want to save playlists you'll have to do some Googling as I don't have playlists so I didn't worry about those when I moved!