but what programs = worthy of useing an 8 core ?
I already told you, heavily multi-threaded programs like renderers/compilers (for the price anyway, the Intel i7s can still go toe-to-toe with AMD octocores).
NO computer will last "a really long time". Technology marches on at a fevered rate and there are some applications that even the most powerful home computers will struggle with. wants a computer that will last a really long time and be able to do anything with out slowdown or issues and have lots stuff running at same time with out any lagg also wnat do it on max settings .-.
In your quest for more cores you've completely ignored the power of each core which I explained to you and you're ignoring other factors too. AMD's octocores are actually two cores per module and this design can hamper it in some instances. It's not a simple matter of "more cores = more work able to be done".
If after all this you STILL want an octocore for whatever reason you might have, just go ahead and get it.