Vista SP1 Rocks!
I have installed Vista SP1 on my Media Centre, wife's PC and my high performance gaming machine and it installed and worked flawlessy in each case Absolutely no complaints at all. All machines are running theHome Premium edition.
Under SP1 the system is snappier from a response point of view, boots and opens applications faster (I've had no issues with Nvidia or Realtek drivers either).
So from my point of view SP1 is great, get on and install it. If you don't like it then you can uninstalls it too.