I personally think that "future proofing" is a myth now more than ever. Whether you build with the E8400, or go the i7 route, there is a good chance that either way, as fast as technology is moving, both builds will be obsolete to some degree, within a short period of time.
Just from a gaming perspective alone, the rig in my sig is not exactly state of the art like when I first built it...BUT, it still runs every game on the market at high settings...I don't have the best video card available, I don't have a quad core cpu, and I don't have multiple GPU's, and my rig still tears up the latest games. I find myself in wonderment at people who pay the price for SLI, tri-SLI, or even quad SLI...what games are they running that require that technology?
As far as Gigabyte goes, I have 3 Gigabyte boards that were all under $100, that I purchased over a year ago, and all are still flawless in their performance.
I think sometimes when people ask questions in a forum like this, they already know the answer they want to hear. If you want the latest and greatest, be prepared to pay for it and just go for it. It may hold you over for slightly longer, but in the end you have to be satisfied that you got the most bang for you buck.
So in conclusion, as long as my current rigs can play games at suitable frame rates, I am not upgrading...I have no desire to "keep up with the Jones'". Rant over...