On The Fly Image Resizing

Hi All,
Looking to implement on the fly image resizing, so my client can upload an image,
and the code will resize it to the dimensions I specify..

Been looking at http://www.wprecipes.com/how-to-resize-images-on-the-fly
And
http://shiftingpixel.com/2008/03/03/smart-image-resizer/

But no luck getting it to work...
Would be insanely helpful if this worked... no more image resizing for my clients!

Any advice would be much appreciated!

Cheers,
Justin

Ive also tried the phpThumb snippet and a few others with no luck! Any help or suggestions would be much appreciated!

For your users/editors, there is a plugin called DirectResize that could be so usefull. If a user upload an image to tinymce content editor and then manually resize it, it creates a new resized image with a link to show it at the original ( or maximum ) size.