Measuring a users connection to the website

Is there anyone in here that has done any kind of measuring of the users connection to the website, I need to do this since we're going to deliver alot of webpackaged authorware macromedia pieces to the users, and depending on the cnnection that he has, we want to send different versions of the pieces, for example, a modem users shouldn't get sound and moving pictures, an oc3 user should get superior graphics and sound, and so on.. Thanks in advance, Mattias, aka bad2da on efnet #php