There is no need to get an i7 unless you are ripping on it, the day to day operating speed on both will be the same, (albeit a tiny bit lower) than justifying it's price increase. an i7 will outperform an i5 in throttling conditions, such as encoding, rendering and long mathematical calculations.
the i5 ivy bridge series and the i5 haswell processors are about par, with the exception that the haswell (4XXX line) consumes significantly less power, and has a very cheap thermal compound under the heatshield. they both cost the same as of writing.
get a K series chip so down the line you can overclock it.
save the 100$ get an additional 8gb ram (16gb)
and I cannot stress the importance of you getting a SSD for your operating system, and ultimately a separate SSD for your applications and cache files/pagefiles.
I have built my
computer over the years upgrading here and there.
my Main PC is
i5 2500k stock with the hyper 212 EVO cooler.
16 gb ram
128 gb OS ssd
128gb application SSD
raid-10 data drive
geforce 780ti classified
it's a few years old, but I keep upgrading, my next upgrade will be a z87 motherboard. (or z97 if a better one comes out)
my backup pc is
Q6600
8gb ram
21tb quasi-raid4 (unraid) (8x3tb drives)