EOSViewer, the software which comes with the camera, does allow you to connect the camera to your PC using the white USB cabble and you can use the software to control the camera & shoot. However, you won't see a preview image on PC before shooting.
The benefit? Images go straight to your PC instead of your flashcard and you can view your pics right away in a bigger screen than your small in-camera LCD. I found it very useful in my autofocus practice shoot
You can also have it write to the card as well as the hard drive. I tried this on a shoot but it took L-O-N-G, so I disconnected it and went back to shooting without the laptop. Now the laptop does not have a hi-speed USB and that may be the reason it was slow. I like the concept, but just found it to be slow maybe with faster equipment it would be worthwhile. I remember it was called "Remote Capture". If you have the time it is great, but I was shooting a team with a line waiting. I felt rushed and gave up, but I will try it again if I get ahold of a hi-speed capable laptop.