did you get the update from the apple site or software update?
in the past when a new version has been released i have got it from the apple site first and once or twice it has been the previous version that i downloaded.
Yeah, but the new GUI was included in 5, and "just for you" is a new feature of the iTunes Music Store, not iTunes the application. I think something went wrong and you ended up with 5. Try redownloading iTunes 6 from apple.com and installing it.