Multiple themes,themes in general

Hello,
I am currently building a media website and new to wordpress, im currently puzzled as to what options I could do about having a flash banner in one part of my webpage and not the other in wordpress, I am currently creating my own wordpress theme.I am not sure if its possible to have multiple themes running in wordpress e.g one page using one theme and the other uses another wp-theme, that was my idea as to solving a flash banner on one page but not the other. If someone could suggest to me another option or if its poissible to uses multiple themes guide me on how to do so that would be greatly appreciated.

Many thanks
Charles.