Here are some links depending on if you have Mac or PC.
Mac:
http://www.oldapps.com/download_iTunes_mac.php
PC:
http://www.oldapps.com/itunes.htm
Unfortunately, with iTunes being so integrated with the OS, downgrading can be tricky and we can't be held responsible for any damage. You can try to rename the application to iTunesNew and then run the install if you have problems and you'll have both versions at the same time.