I installed the entire disc, and then the updates from Canon's site (some require a pre-existing version to be installed). I reality all I've used so far is EOS Utility (communicates with the camera and does tethered shooting) and DPP (raw processing).

There's also some management software I don't know if I'll ever be using (ZoomBrowser EX), Photostitch (which I'm sure I'll want to try at some point), picture profile editing stuff, some movie editing stuff, plus a bunch of "CameraWindow" utils that don't actually work with my model.