OMGness thanks so much, you really cleared up a lot of questions i had. Fortunately/unfortunately i now know that you are a ready source of music knowledge :D so i have a few more.

Why is the add9 chord different from just the 9? Example, Cadd9 is C E G D but the C9 is C E G D Bb? why is the flat there?

BTW i am using a nifty program called scale tools.