The best hardware to take advantage of DF is as follows

Fastest mhz chip speed. number of cores doesn't matter as DF can only utilize one of them. This is the primary bottleneck in DF for modern hardware. Basically it would run faster in DOS with a single core pentium 4 than on modern hardware. (basically you would get worse performance from a multi-core processor because they are usually clocked slower.) I have a quad-core clocked at 2.3 and I think the fastest P4 was 4.2 IIRC.
Fastest memory speed. this will help with memory bottlenecks, which from my experience is not the issue.
64bit will not help DF nor will the LargeAddress flag (except in rare worldgen crashes)
Your proposed upgrade would probably close to double the speed of DF as you would be trading the 2.4ghz for the 4.2ghz clock speed.