Intel processor that will last till the Haswell release, preferably Skylake?

you'd may as well wait for ivy, as it will be more likely to last longer.

however it will still work and be viable come haswell (1 year) and skylake (2years?) look at the first core 2 quads, they are still perfectly happy for gaming.

For your chem stuff, if the calculations get more complex then you'll have to wait a bit longer.

It also comes down to the fact that the software industry is at the moment lagging behind in the use of the power they have access to, partly due to the lowest common demoninator, and partly because they don't know what to do with it, kinect is an example of the use of that power.

Do you think that more realistic simulations will be coming down the line needing more power? if they are it'll probably 10x-100x more power, in which case nothing really helps you.

The 2700K should "last" a long time. Apps are becoming more GPU aware so you can probably just pop in a new video card when the need arises.

Any Sandybridge will last 4-5 years regardless, just buy a i5 2400 or 2500K (if you overclock)

Then you can use ivybridge processors because they use the exact same socket.

With Haswell out in 2013 and on a new socket, if you are legitimately looking for that then you may want to do a modest cheap 1155 build say a i3 2100/Pentium and a H61 motherboard, put the money towards a higher end GPU either a Nvidia 600 series or Radeon 7000 series card, wait a year then move on up to Haswell not having forked out $800+ on a sandy or ivy.

Will Sandy Bridge or Ivy Bridge last you until Skylake? Maybe. maybe not. It depends on how much performance is enough performance you as time goes on. 2016 is 4 years away.

I built my PC with a Q9450 back in 2008. I'm waiting for Haswell to upgrade so by that time the Q9450 will be 5 years old.

Hopefully the performance increase from Ivy Bridge to Haswell will not be like the performance increase from the Phenom II to Bulldozer. I'm pretty confident that Haswell's performance will be good.

I have my old Core2Duo E6800 bought back in 2006 running a 560Ti and it is handling Skyrim, F1 2011, and some other games the youngsters play on maxed out settings. The poster above should be more than happily running games and whatnot on his C2Q, simply put a sandybridge will not deteriorate in performance that quickly, in 4-5 years time it will still game like a beast.

Easy peasy, cheap sandybridge build, higher end GPU/PSU, sell Sandybridge in a year, carry over some components to the haswell.....badum tish.