One more thing for Windows users; Set Windows>Sound>Properties to use the on-board sound card as it's "default playback" device(leaving the interface for Pro Tools use, only).
Re the IO setup, it is well worth some time getting to know how/why certain things work(and certain things sometimes don't
). Customizing to suit your needs can really streamline your workflow
In my case, since I have 30 channels of outboard preamps, I found it best to name my inputs according to the preamp that feeds each(as in Midas 1, Midas 2, ISA 1, Vitech 2, etc). Then I also named the output side(Main Out, Phones Voc, Phones Bass, Phones Gtr, etc). With an Mbox, things are easy to keep track of, but as your setup grows, don't be afraid to "grow" with it