That dynamicdrive loading bar is time based, meaning it has nothing to do with if everything is loaded. I built a loading bar for images based on if they all loaded using document.images.complete I found that each picture had to be loaded one by one into a hidden div to function properly.
From an old thread, I dug up this.
If you want, I could build you a easy snippet of code, but I might not be able to get to it for a while. The code for a loading bar I am using has ugly code so I wouldn't give that to you right now.