Image compression & Image Quality

Question

Hi,
I have a site that has a Swf Background where it fills the window completely, so the image isn't static. My only problem is, as it stretches obviously the quality degrades, and i would like it to be quite smooth however it's viewed, but also i need the file to be quite reasonable so it doesn't take ages to display. My Background fades in and out through 3-5 images (the reason the file is quite big, around 500kb+) and i have a progress bar while it loads.
Does anyone have any ideas how i can keep the image quality quite good when it's enlarged without the file size being too big.
I fear this might be impossible

Answer 1

Great thanks,
Do you know how i can load multiple images into the swf, i'm currently using the following script on frame 1, which loads the first image and voilà!  but what i done was to duplicate this on Frame 2 to load the second image and so on (as i don't want them to all load at once, i'm thinking this might increase the download time) but suddenly it no longer works.
var imageLoader:Loader;
function loadImage(url:String):void {
imageLoader = new Loader();
imageLoader.load(new URLRequest(url));
imageLoader.contentLoaderInfo.addEventListener(ProgressEvent.PROGRESS, imageLoading);
imageLoader.contentLoaderInfo.addEventListener(Event.COMPLETE, imageLoaded);
loadImage("Bk01.jpg");
function imageLoaded(e:Event):void {
imageArea.addChild(imageLoader);
function imageLoading(e:ProgressEvent):void {
Much appreciated!