xaira :
just get the highest clocked quad core you can find, there are no mobile hexacores available yet, make sure you get a nice 512gb ssd to go with it
Have you seen the prices/specs of those CPUs?
Intel® Core™ i3-350M 2.26GHz (3M cache) [Included in Price]
Intel® Core™ i5-540M 2.53GHz (3.06Ghz Turbo Mode, 3M cache) [Add $200.00 or $6.00/month1]
Intel® Core™ i7-620M 2.66GHz (3.33Ghz Turbo Mode, 4M cache) [Add $300.00 or $9.00/month1]
Intel® Core™ i7 740QM Quad Core Processor, 1.73GHz (2.93GHz Turbo Mode, 6M Cache [Add $300.00 or $9.00/month1]
Intel® Core™ i7 840QM Quad Core Processor, 1.86GHz (3.20GHz Turbo Mode, 6M Cache) [Add $600.00 or $18.00/month1]
Intel® Core™ i7 940XM Quad Core Processor, 2.13GHz (3.33GHz Turbo Mode, 8M Cache) [Add $1,200.00 or $36.00/month1]
World's fastest mobil Intel processor
That's from Aleinware.
Spending $1,000 on a CPU that will be like a $200 desktop CPU is silly IMO (unless cost isn't a factor).
As you can see, OP. The 9xxXM has 8MB L3 cache (compared to 6MB on the 8xx/7xx), and a 133MHz advantage over its predecessor. Mind you, desktop CPUs still only have 6MB L3, so it could say 8MB for such low clocked CPUs is overkill, IMO... They (9xxXM) also have a 10w higher TDP.
If it was me, I'd go for nothing more than an i7 840QM. And TBH I'd probably go as low as a 740QM, or even go for the 4MB L3 i7/i5.