Hi! Below I have a little video I need abit of help with. I have three characters, all thinking about things.

http://www.gorecartoons.co.uk/bub001.wmv

I want to make the "thinking" clips into the shape of thinking bubbles, like in comic strips.
Anyway of doing this in premiere or is it an after effects job, and wat methord is best?
Even just a sphere shape would do.