Need guidance - trying to get the best value from a new workstation build

[minraise]

I'm interested in building a workstation that can handle the following activities without a problem:

• running 4-8 simultaneous VMs (each requiring little CPU and memory)
• web design in Photoshop/Illustrator
• software development in Visual Studio and other IDEs
• moderate video encoding/decoding
• infrequently (~monthly) running simulations requiring raw computing power and as much RAM as possible

After doing some research, I've put together a few build configurations (CPU/Mobo/RAM only, budget < $700) that I'd love for you to critique:

[1] Phenom X3 720 Build ($267)

• Phenom X3 720 + GIGABYTE 790X-UD4P ($219)
• GSKILL 4GB DDR2 800 ($48)

[2] Phenom X4 940 Build ($318)

• Phenom X4 940 + GIGABYTE 790X-UD4P ($270)
• GSKILL 4GB DDR2 800 ($48)

[3] Core i7 C0 Build ($570)

• Core i7 C0 stepping from Microcenter ($250 after tax)
• ASUS P6T + GSkill 6GB DDR3 1600 (Combo) ($320)

[4] Core i7 Possible D0 Build ($600)

• Core i7 (from Newegg - chance of being D0) ($280)
• ASUS P6T + GSkill 6GB DDR3 1600 (Combo) ($320)

[5] Bloomfield Xeon W3520 D0 Build ($626)

• Xeon W3520 D0 ($306 after shipping)
• ASUS P6T + GSkill 6GB DDR3 1600 (Combo) ($320)

[6] Suggest a build? (< $700)


My goal is the get the best value for the money, considering performance, longevity, and power consumption (as the machine will be on 24/7). I am also going to be overclocking to gain additional performance.

The question I am having trouble answering is "If I go from build X to build Y, is the price difference justified considering performance, longevity, and power savings?"

Regarding power savings, I'm fond of the i7 with D0 stepping because, compared to C0, it allows for higher overclocks at lower voltages.

Any and all advice/guidance/suggestions is greatly appreciated!

 

[ou_phidelt]

Regarding power savings, I'm fond of the i7 with D0 stepping because, compared to C0, it allows for higher overclocks at lower voltages.

Right there is your answer. Of all the listed combo's that will give you the best performance/watt.

 

[BG-0]

I would say D0 920 or PII x3 720. Yet, if you have the cash to shell out, i7 may offer slightly better longevity, as well as a little better value for money. +/-5%, but still.
Just looked at the tasks mentioned, go for 920 D0.