Upgrading from a 6-year old P4 to play games..HALP!!

Here are my current PC specs

Pentium 4 2.6 Ghz
1 GB RAM
GeForceFX graphics card (64mb)

I am finally upgrading to a new machine mainly because I want to get back into PC gaming. My only concern is that the game I want to play most is Doom 4 and may not come out for another two years and I would like my machine to max it out. I understand and expect that I will have to upgrade my videocard by then...but I hope to buy a starter machine now (i.e. a Dell) with a CPU that is future-proof for optimal Doom 4 requirements.

Things are not what they used to be....I hear CPU is not so important for games anymore. Would an Intel i7 be future-proof enough?

thanks

I'm currently monitoring slickdeals and other sites for Dell deals. When I see one I am planning to move fast...I'm not going to get the best video card right now nor am I even planning on getting much RAM as I can buy that cheaper on my own and in the future as needed.

My main concern is the CPU...something like an I7 2.8 Ghz is within my budget. I dont have a $$$ value but I hope to not pay for diminising returns (i.e. $100 for an extra 0.1Ghz clockspeed does not seem worth it). My main concern however is gaming (particularly doom 4) and I was under the impression that games are much more GPU-centric than CPU.