Image resizing app - better quality than automator?

I am in need of an application to resize 10mp images from my camera down to 640x860 and similar resolutions for use on the web.

Automator has the ability to scale images, but really destroys the quality - using a program called faststone on my pc seemed to do a good job, whereas automator ends up with the images looking very soft and blurred where I know they are very sharp.

What options do I have for better quality?

I am currently using the free Canon DPP editing software, and occasionally GIMP if that makes a difference, but neither can handle batch processing...