After reading various posts in this section, I decided that . . . there's no real consensus on certain issues
So I decided to wait until Microcenter had a sale on components that I was considering and let that guide my upgrade (Microcenter does not have a store in every state, but it's totally worth it to look at their website and get on their e-mail list for weekly specials).
I kept my case, power supply, GTX 460, blu-ray burner and drives, and bought:
Intel i7 2600 LGA 1155
Asus P8P67 LE (B3 revision)
Patriot 8 GB PC3-10666 memory (package price last week for all three items - $409.97)
I thought I was done, but then I discovered (before installation, fortunately) that my existing Windows Vista 64-bit system builder software couldn't be used with these new components (Microsoft links OS activation to the specific components). So, I added:
Win 7 64-bit Home Premium (on sale this week for $87.20)
New Seagate 7200 RPM system drive - $59.99 (just in case I really needed something off my existing system drive)
With that, I thought I was done, but once everything was up and running, the CPU temperature immediately ran into the red. So I added a Corsair H60 CPU cooler ($79), and I'm seriously impressed with how well it works, and how quiet it is not to have a CPU fan.
Total outlay: $636.16 (plus 6% sales tax).
PPBM5 Benchmark Total Time:
Old system (Intel Q8200 quad core) - 820 seconds
New system - 363 seconds
New system with Asus auto overclocking settings - 343 seconds
So I may not have the best system money can buy, but I'm very happy with the improvements. And I'll probably turn off the overclocking since the benefit is relatively meager vs. the potential damage to components.
You would do well to double up on the memory, it will improve performance immensely. I looked at your data. If you want another major improvement it would be to add at least a second disk drive for a RAID array on your project disk