i7 2nd gen, High speed or Multi-core, which to prefer?

[Mahesh]

Hi, I want to buy the laptop for my software development work.
I want it to be future-proof, especially in terms of its processing power.

Thus , I kept my min processor requirement to buy i7 2nd gen (without giving preference to other features like backlit keyboard, surround sound, HD Screenetc., even I am opting to 4GB RAM against 8GB as I can extend it in future)

But i7 processors are too much costly.
However, I found one laptop by Dell with 2nd Gen i7 processor

The processor sprecs:
2nd generation Intel® Core™ i7-2630QM processor 2.00 GHz with Turbo Boost 2.0 up to 2.90 GHz, 4 cores

The price of the whole configuration in India is 55000 Rs (INR), as on Dell's site.

But I have confusion:
As you can see its marked speed is 2GHz

Now the same configuration may include i5 at cost 52388Rs
i5 Specs:
2nd generation Intel® Core™ i5-2410M processor 2.30 GHz with Turbo Boost 2.0 up to 2.90 GHz, 2 cores

The marked speed is 2.3GHs, but it is 2 core, while above i7 is 4 core.
Yes, but both have Turbo Boost 2.0 upto 2.9GHz.

So which to prefer? Which will give me the better performance.

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Some Questions

One question: Does this Turbo Boost is always applied, so that I can get 2.9GHx performance all the time? I have read the factors that limit Turbo Boost (like active cores, TDP etc.) I want to know if there are any experiments, survey that tried this (running in Turbo Boost mode for long time).

How I can get max out of Turbo Boost.
Is there any way to ease those factors that limit the Turbo Boost?
• Number of active cores
• Estimated current consumption
• Estimated power consumption
• Processor temperature (can it be eased by working in cool place, low temprature, more boost !)

One more question: Is i7 power hungry? I am afraid of getting reduced power backup.

Another question: Is this i7-2630QM worthy enogh?
I think its lowest end i7 with Turbo Boost 2.0 upto 2.9GHz (while other i7 have upto 3.4).

Is it better to go for some Core 2 Duo for speed near about 2.53GHz insted of Intel Core i-series with less speed? Will it provide more performance?

Final question: Is there better configuration than this?
I need:
Intel 2nd Gen Processor (or any you will suggest in my budget)
Min 4GB DDR3
Min 250 GB HDD
15.6" Screen

I found this configuration on Dell-India site:
http://www.dell.com/in/p/xps-l502x/pd?p ... ref=gzilla

I know I am at right place to ask all this. I trust your knowledge. Thanks.

[Sttm]

The core i5 chip is a dual core cpu, while the core i7 chip is a quad core cpu. The i7 chip should use the turbo boost feature to clock itself at 2.9ghz when only using 2 cores making it the same top frequency the core i5 can do. But the Core i7 has 2 more cores so if you use heavily threaded applications it will be much faster, and the core i7 chip also has double the cache, 6mb compared to 3mb, increasing performance there too.

The core 2 duo is very slow compared to the new 2nd gen Core i7 or i5 cpu, Intel has made numerous improvements to the architecture that increase speed and efficiency. At the same ghz, say 2.5ghz, a Core 2 Duo would probably be over 50% slower then a Core i5 or i7 2xxx chip at 2.5ghz.

I would buy the quad core i7-2630QM based notebook. The speed increase should be well worth it for software development.