The EOS utility allows you to remote control the camera, big woop.
However, it does also allow you to easily download and view, only UPDATED or NEW images from the camera. This is a great benefit, if you don't like to clear cards immediately after shooting. (as you can use the cards as temporary backup)
Zoombrowser is started automatically after EOS has downloaded the images. It allows you to quickly view and select images
DPP allows you to process the raw images, and I have found its processing is a lot more accurate than CS2. It can apply the noise correction and lens correction to the images depending on lens, even if these were selected as disabled in the camera.