Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
You just copy it. It should carry over the artwork and the ID3 tags.

Not necessarily. It would work only if the artwork is embedded in the file itself, not if the artwork was downloaded from iTMS using "Get Album Artwork" command.

To check whether the artwork is downloaded or embedded, right-click the track and look for "Clear Downloaded Artwork" menu item. If this command is visible, artwork is not embedded. In that case you can bring up artwork window (either in Get Info > Artwork tab or the small artwork viewer in the bottom left corner), copy and paste back.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.