AJAX File Upload with PHP

I need an file uploading system that is similar to what you see on [login to view URL], [login to view URL], and [login to view URL] This system works with AJAX technology to give the progress of the uploading file(s). In my system, the backend should be in PHP/PERL. Also, it should allow for multiple file uploads similar to what is on [login to view URL] offers. Another component must be added to this file uploading system as well. Before the files get uploaded, a check should be done to see whether the total number of bytes for the files selected does not exceed a predefined max upload size. Lastly, this system must be extremely effecient and fast. The script must be Object Oriented and well documented. It must be optimized for fast loading and performance. It must be compatible with all browsers (IE 5+, Mozilla/Netscape/FireFox, Safari, Opera). It should not crash the browser and mostly importantly, it must give accurate data on the file upload progress.