PHP upload script mod to speed up Image Upload

I have a PHP upload script for a classified adverts website. It allows for the advert and 5 images to be uploaded. When the images are uploaded they are manipulated by the PHP script. However as the images may be large, the image upload can often take too long and even time out. I need to integrate some sort of AJAX, JQUERY or JAVASCRIPT method to chunk the images before uploading them to the server, they can then be passed to the existing script to complete the actions on them such as rename, watermark etc. I need this to speed up the upload of the images. I originally wanted to use Plupload tool but will use whatever works. Current page can be seen at [login to view URL] You may place an advert to upload images but do not confirm it as site is live, Thanks