I've recently built a new system and have been using it for about a month:
CPU: i5-2500k @ stock
MOBO: Asrock Extreme3 Gen3 z68
RM: G.skills 2x4GB 1600
GPU: HD 6850@stock
SSD: Corsair Force 3 120GB
Cooler: Corsair a70
It runs very well. I mainly use it for surfing, looking up journal articles (tons of PDFs), and working on papers/documents. I occasionally play some Skryim, which it seems to handle just fine on maxed settings with an old monitor (might even be like 1200 x 800 res or so; not at the computer at the moment).
When I purchased the CPU, I did not quite understand Intel's chip release strategy (I hadn't kept up with components at all actually until I started building). I knew the MOBO could take IB, but didn't realize that the performance jump would likely not be much, and did not realize that Haswell should be a more substantial jump that the MOBO can't take. I would like for this computer to be good and fast for my purposes for a while, which will occasionally include large Excel spreadsheets and some very minor data crunching (most of which the P6600 in my laptop handles fine, though it doesn't like loading large data files). So I see 3 possible plans for the life of this MOBO:
1. Just stick with the i5-2500k and OC it in a year or two (or more).
2. Eventually replaces the i5-2500k with an IB 3570k or 3770k, which largely would depend on how quickly office and normal-use software starts making use of all those threads as far as I can tell.
3. Sell the i5-2500k, get the G620 ($80) or G530 ($52), and in a year or so get a 3570k or a 3770k.
Which seems most reasonable given the above uses? I would like for this computer to last as long as possible. Given that, how much do you think a 3570k would add to the high-performance life of the computer over the 2500k for the above uses? If not, then option 2 isn't wise. That leaves option 3, which has me essentially paying $80 or $52 as a stopgap for a year or so before paying $200-$300 for the IB chip.
It probably depends a bit on how OCable the 3570k is; some think the lower TDP will mean higher OCability, while others point to the smaller process being able to take less voltage. The issue right now is that the window for selling a slightly used 2500k for $190-$200 is probably closing (I paid $200 for it, so that price would be great to me). Any thoughts would be much appreciated!
My advice is that you keep the Intel® Core™ i5-2500K and get a couple years plus out of it. Our next generation Intel® Core™ processors are going to be a die shrink and there will be some improvement to the IGP (Integrated Graphics on Processor). In the end the performance increase on a die shrink (even with the move to tri-gate) is not going to give major performance improvements. Since the Intel Core i5-2500K can easily be overclocked you can get performance that can last for years to come.
In 2 to 4 years it is possible that that software may have developed to the point of needing to upgrade your system but I think that it is going to be on the later over sooner in that time frame.
Keep the i5 2500K overclock it to best stable performance and it will a future prooof for about 2-4 years. Your laptop will not handle much data maybe because it needs more memory, try adding more memory.