Always upgrade

As far as your cable choice, uhmm, a little overboard with the expensive Monster....
DVD player, well the 3910 is nice. What exactly are you looking for in a dvd player. The format war, may take more time than what you are willing to wait for. There are going to be players that will be able to play both formats (personally, I would wait for those players)
Are you looking for connections? Upconverting? What kinda budget, clearly the 3910 is high budget, are you willing to go that high?
By the rest of your system, I am assuming you would. But would you prefer best bang for buck?
I'm just rambling. Also you may want to wait for Tom, Clint, and Gene to finish at the Cedia show. They may have some new contenders coming out that may be worth a look.