Can't play music in Library upon transfer to new computer

Question

Trying to move my library to a new computer. My I-pod is broken (otherwise I'd use it as a "hard drive" to transfer the music, so I used an external hard drive. I copied the iTunes folder from the old computer to the hard drive. Then downloaded the newest iTunes version on the new computer. I transferred (or at least I think I did) the library to the new computer. When the external hard drive is plugged in, I'm able to click on and play any song in the library. However, when I unplug the external hard drive and try to select a song, I get a message stating "the song (name of song) could not be used because the original file could not be found". I am assuming that I somehow didn't transfer the files correctly, but I'm at a loss for how to do it. The new computer is Vista, the old was XP. I'm familiar with XPs capability to open Window's Explorer and copy and paste from one place to another. But I don't see Window's explorer on Vista and therefore don't know how to copy and paste from one drive (in this case my exteranl drive) to the C drive on the new computer. HELP!!!

Answer 1

Hi Sunshine Coda
Since no one has yet responded with a definitive answer try this:
Open iTunes.
From the Store menu, choose "Deauthorize This Computer…"
Enter your account name and password.
Click OK. A message appears reading "This computer has been successfully deauthorized."
Click OK.
Repeat steps 2 through 5 above. If you see the same message reading: "This computer has been successfully deauthorized," then your computer was using multiple authorizations.
Continue to repeat steps 2 through 5 above until you see a message reading "This computer was not authorized. To authorize this computer, play a song or video you have purchased using this account."
Then, try to play that song again. You will be asked to authorize the computer, after which the "already authorized" message should cease appearing.