I am going to get the new 27' iMac with the 3.06GHz Intel Core 2 Duo processor and 4GB of RAM memory.

I want to edit HD video, like, I want to keep this computer for a loooong time, and when I have enough for a really expensive high quality video camera, I want to know that the computer will still be able to smoothly edit these videos.

Or, I could upgrade to the 3.33GHz Intel Core 2 Duo for $200 and 8GB of RAM for an additional $200.

But I only want to do that if I have too.

What do you suggest? Which of the two would I need more?