After MUCH research and helpful guidance from Harm and others, I have narrowed down my spec to either of two options. Both are gradual builds over 2 months as budget allows.
i7 2600K with 4Gb and use inbuilt HD3000 graphics to start
add GTX 460
add memory to total 16Gb
i7 950 with 6Gb and 5450 to start
Add memory to total 12Gb
swap out card to GTX 460 (the 5450 will go to another machine, so will not wasted)
These will be accomplished in 3 steps over 2 months.
Any final comments, suggestions before I make my choice will be really VERY much welcome. I've learned a lot here, but I'm still not super confident I am doing the right thing ...
It sounds to me you are on a tight budget.
Your first priority is to increase memory to either 12 or 16 GB. That means after you have three SATA disks available. If you have the disks and know the cost of the memory, you can decide on the i7-2600K or i7-950 with their respective platforms. In your case I would let the budget decide. Both are very good CPU's and the relevancy of the limited PCIe lanes on the P68 platform may be nil in your case, because it does not sound like you have the means to buy a dedicated raid controller in the foreseeable future anyway.
Sorry if I misunderstood you and made false assumptions.
Which motherboards would you be using for your system for the two possible CPU selections?
What case will you be using?
What power supply?