I still want to know why? Not a dumb, argumentative question: I really do question the reason for these Intro splash screens, Flash or otherwise. What conceivable advantage do they confer? Why make people click on a useless page to get to the actual site? It really does smack of the triumph of design over function (but then, I am an engineer by education, training & temperament...). However fast you make it load, why is it there in the first place?
As far as I am aware, there is no practical way of knowing if the user that connects to your web server is on dial-up without running a script that will take at least as long to run as loading the Flash script anyway. Oh, guess what? No music either please Not a problem for me as I have the speakers switched off anyway for that very reason: music on web sites = yuk!
Just because you technically can do something, does not mean that you should do it...