It's been a while since I've read about anyone upgrading their processor!
Yes, it is very possible; come to think of it, it's probably easier to swap out the processor on a laptop than swapping out a discrete GPU, which is soldered to the motherboard. I think the CPU is actually just plugged into the socket on the motherboard.
The real problem you'll have is that the only way to get to the motherboard is to dismantle the whole laptop. And I mean really dismantle the whole laptop, with a screwdriver and more patience than I care to imagine.
Is it worth it? No, absolutely not! Between the i5-2410 at 2.3GHz/2.9GHz turbo and the i7 at 2.7GHz/3.4GHz turbo, you're gaining...500Mhz at most. That's a base speed bump of 15%.Since it's the same architecture, you can compare accurately using clock speed alone.
Is 15% worth seeing your laptop dismantled and splayed about a desk? Only if you're really enjoy the work.
If your i5 seems slow, check in the Power Manager to make sure you don't have your processor power cranked down low for battery and heat savings. Click "maximum turbo" in the advanced settings.
For the record, I have an X220 with that very i7-2620, and most of the time I have the CPU underclocked to "low" in the Power Manager settings--which causes the processor to fix itself at a paltry 800Mhz, less than 1Ghz, and it's still faster than my old laptop or my Atom netbook that runs at 1.6GHz.
Firefox scrolling is much smoother when I crank the CPU up to "Balanced," which sets it jumping between 1GHz and 2GHz. Clocking it up to "Turbo" at 2.7GHz does make things a little more fluid here and there, but the chassis starts to get warm and the fan cranks up, and if I'm on battery, the battery life gets clobbered.
So through all my regular use, I really don't take advantage of the full 2.7GHz/3.4GHz clock speed of my i7. Nice to know it's there, but that's it.
Unless you're constantly doing video or photoshop editing every day, I doubt you'll even notice the difference between an i5 and i7.
If you want application speed (load times), spend the money on an SSD? [7mm height for Thinkpads, not the common 9mm, I think.]
