I'm certainly glad you guys cleared that up. It's a little pet peeve of mine when people try to say Aerith, as a "th" instead of an "s." Like I tried to tell my friends back home, it's the same pronounciation, regardless of the spelling.
Though I had the reasons behind it wrong. I had always heard that her name was Latin. And in Latin, "th" is pronounced "s." You guys ever listened to One Winged Angel? The choir pronouces it "Sephiross." But....it's a personal preference of mine to say Sephiroth (pronounced as spelled).I likes it.