W510 which CPU i5 560m or i7 720qm concerned about noise

[live4fun]

I am almost ready to close the deal on a W510 but I hesitate cause I am not quite sure which CPU to choose.
i5 560m Dual Core (TDP 35 watts, 32 nm) or i7 720qm Quad Core (TDP 45 watts, 42 nm)

Which one off the CPUs will provide me with lower noise levels during office task: programming, surfing etc.
A: Does it make a difference?
B: Does the 10 watt higher TDP of the quad core of 45 Watt only matter under full load?
C: Which CPU draws the least power in power saving mode (forced to slowest clockrates)?
D: Does the fan noise in office/idle scenario get any louder regarding the choice of cpu I make? Or does the cooling system handle both thermal envelopes equally.

One Advantage is the AES support of the i5 CPU. Well the i7 just has two cores more, so should easily handle encryption as well. I plan to use full disk encryption.

I of course like to get the most power for my money, but a silent work environment during office hours is mandatory to me. I am an computer science student and thus use the machine more than 10 hours a day. Professional as well as leisure use.
It has to compete with my now broken Mac Book Pro when it comes to being silent under idle conditions.

I really liked the low emissions on a friend's T510 with core i7 620m.
Do the W510 and T510 have the same cooling system? If so I'd guess, to put an addition 21 Watts (35-14) on it, for the faster GPU, already put's medium load on the system, while an addition load of 10 Watt, by the CPU, would push it to heavy load.
Is there any fault in my logic? Do they have differing cooling systems? Do the cooling systems of the different W510 configurations eventually differ?

Can you offer me any advice on which configuration to choose? Prize difference is marginal with my student discount. Battery life ain't my concern either.
Anybody having experience with those machines side by side preferable in an silent environment?
I'd really appreciate your comments on this issue

[thitiv]

I notice many people reading your question. It takes time to answer all your questions.

I just switched from a ThinkPad T500 with Core2 Duo T9900 3.06 GHz to a W510 with Core i7 720QM. There is virtually no difference in terms of noise. In a very silent private office at work, I can barely hear any noise from the machine, except of course the CPU whine which still occur from time to time. The quad core i7 may consume more power at full load, but not always. That's why you need a 135-watt charger to make the machine run at its full speed.

In short, go for the i7 if you would like. It makes no differences in terms of noise!