Dressed up to the nines - dressed as beautifully, elegantly and smartly as possible.
At sixes and sevens - being in a state of confusion, mental disorder, not being quite in control of oneself.
The song Don't Cry For Me Argentina (of the musical Evita fame), has these words
You won't believe me
All you will see is a girl you once knew
Although she's dressed up to the nines
At sixes and sevens with you