Unfortunately autorun does not work for USB flash drives. You will simply just get the generic autorun box that windows produces. You could do it with a CD though, have it open some OpenGL applet with a message or something. Lookup autorun.inf and the parameters. (I forget myself how to do it, but it's pretty easy)
I think there IS a way to get autorun to work on a flash drive, but since it's off by default, you can't really depend on that unless you have access to the PC she will use so you can change it ahead of time.