Hey... i was wondering if anyone would mind helping me..

I have a lot of images that are being called from my server using php but when they are displayed they are all either bigger or smaller than each other... What i need is a way of resizing the image so that the width is equal to 200pixels. The height of the image is not important but i need the image to be scaled down so that it does not look squashed/stretched. Can anyone please point me in the right direction??

Thanks, BIOSTALL