If you are only interested in flying helis, I wouldnt get a RX/TX kit that comes with servos.  You most likely would never use them in a heli.  But, if you ever plan on getting into planes as well...then I would.

The DX7 or 8 should serve you fine with whatever helis you get into.  I have a 7 and fly anything from my mSR up to Raptor 50 with it...and its fine.