PC for semi pro use: where I have to spend, where I can save

[bombonfoton]

Hi, I would like to know the difference between a motherboard with the firewire included and an independent capture card. Is it better the latest?

I would also like to know what intel processor is better right now for professional editing, no matter the costs. I've heard that the "D" one is just a step for an upcoming one that's gonna be real good, is it true? is te Xeon processor just for servers? or is it good for editing desktops too?