I use Graphic Converter to do the same thing... I maintain an ecommerce site. My customer sends me a CD from the manufacturer with images. They are usually a mess, different sizes, formats and resolutions.
With the batch (Convert More...) feature in Graphic Converter. I can select all images in a folder and have th resolution changed to 72, when use max size to make sure that the image fits within the dimentions that I want (129 x 145). This is great because it will queeze in horizontal or vertical images. After this, I use bring to size to padd the images (since they have different h to w ratios) to the same exact size. Finally, all images are saved as JPEG in the destination folder.
Graphic Converter is worth every penny and then some...