jefe323 :
OCing your processor actually decreases its lifetime.
out of those two sockets, i'd say 1156 is 'more' dead then 1366
either socket will probably last you at least 4 years at stock speeds. (i still have a p3 system that runs at stock speeds)
I have never known overclocking to kill a processor, ever. So long as you keep it cool, and don't apply unnecessary voltage, it will outlive the useful life of your computer. In fact, I have a PII system that I used in my early teens that still runs fine.
It is fairly easy to build a pc that will last 5 years, however, you may want to consider the economics of your decision.
1. If you do that now, it will likely cost upwards of $2,000.00 for a computer that is still considered "decent enough" in six years.
2. Other components will likely need upgrading/replacing before six years is up. If you game, your graphics card will stay recent at most for 2 years, depending on your screen size.
3. Hard drives may or may not last 6 years. I've had drives last 10 years, arrive DOA, and die somewhere in between. Count your blessings for a 6 year run without replacement.
Another option is two buy a decent case, power supply, and optical drives that WILL last 6 years. They aren't hard to find. Any quality PS has a decent chance of lasting this long. Then you can buy moderately priced mid-range parts that will get you through, say, three years at at time, then do a refresh.
Example:
I bought a antec 900 2 (expensive for a case), OCZ gameXstream 700W PSU, and HP DVD burner. I plan on keeping these for every new build that I do. Although the case was expensive, I know it will last. The power supply has countless good ratings on newegg, and I don't overload it with components, so I suspect it will last. Optical drives are cheap. HP is a good brand. If it lasts, great. If it fails, its not a huge expense.
Instead of buying a monster LGA775 system a few years ago, I bought a cheaper AM3 based system. Phenom II 955, 4 GB 1333 DDR3, and a 4870, once the price came down. It didn't cost that much. I know that in a few years, I can reuse some of the components, rebuild the innards for around $600.00 and still have a great gaming system.
Do it this way and you'll stay current longer, and have cheaper, more reliable systems over its lifespan.