I like it spelled Zita (I almost used it as my confirmation name). Zeta is a little too Catherine -Jones for me, but overall the sound and look of the name is pretty.:)
Zita just reminds me of Zits and the poor child would hear no end of teasing from elementary school on.Zeta I'm assuming is a surname, as in Catherine Zeta-Jones. It sounds harsh and unfeminine imo.