Site Load Speed?

This is probably a really stupid question, but is there any way you can figure out how long your site takes others to load on average? That way I can be sure to build one that will load relatively past for the people stuck in the stone age, I mean, on dialup service....

You can create a microtimer in PHP and set it to start at the beginning of the HTML code then stop and record it at the end of the HTML. This will give you an approximate loading time. However, it doesn't take into account the amount of time images take to load.

http://www.totallyphp.co.uk/code/page_load_time.htm

This is some help because I might use it somethime in the future, but what I'm looking for is something that could give me an estimation on how long the page might take to load using various types of internet speeds. I'll look around...