Questions Regarding CPU Choices for New Build.

[Vanishing Point]

I have been looking at getting a new machine and a few questions have cropped up while looking for various components so I thought I would try and get some advice.

Mostly I want my machine for gaming but I also want to get something that will require the minimum of upgrading and will let me avoid overclocking any time soon. If people could answer both questions seperately that would help keep things clearer for me.

1) As a gamer is there is there any specific reason I should go to e6600 over cheaper e6400 model. Does the 4Mb cache in more advanced model offer anything to me?

2) I am looking for is a solid system that will last me a while and only require an update to the graphics card in a couple of years time when DX 10 cards are established. Bearing in mind I want to avoid overclocking.

Would this make spending extra money on the higher spec pentiums (6700 6800 Duo) and the faster memory a worthwhile investment, or would the difference between those and the 6400 or 6600 be negligeable enough that it would not justify the extra expense?

Thanks in advance.

 

[Vanishing Point]

I should probably clarify, questions 1 and 2 are sort of seperate issues. Basically there are a couple of us looking at new cpus/systems and we both have different budgets and ideas.

Bearing in mind I am not the most computer literate person, it would help to know the pros and cons for each question.

Sorry if I wasn't clear at first, any help is greatly appreciated, we both feel we have reached a point of indecision in our respective choices.