Download+Install iTunes 10.4 and you should be on your way.
If you get an error follow these steps:
Go to ~/Music/iTunes
You will need to rename iTunes Library.itl to iTunes Library.bak
Go into the "Previous iTunes Libraries" folder where you will find several files with dates in their names. The most recent one will have the .itl extension, but the others don't. Copy that to the parent folder ~/Music/iTunes/ and rename it iTunes Library.itl