I use windows media player for music on this computer. So thanks to a winblows update it managed to turn all of my "date added" data to todays date :'(
I've searched the web looking for something to bring it back with no success but i did find a program called Windows Media Player Metadata Backup for Audio. It makes backups and can restore the meta data of your music; how many times it was played, when it was added, etc.
Figured i would pass it along(yeh it looks like its older but is kept updated and works):http://www.dalepreston.com/Blog/2007/03/windows-media-player-metadata-backup.html