An I7 isn't a need, but I sure do love having one. A 3770/4770 isn't thattttt expensive, just about $80 more than the I5 the OP has picked out. It really depends on what you do, I've been doing some video production stuff lately and I really appreciate my I7.
Also if you keep you eye out you can normally get a similar HDD that's 2TB for around $80, so only $20 more than the one you have picked. Also make sure to look at reviews for the power supply to make sure that it's reliable, there are power supplies out there that while they may seem good can be unreliable and totally fry…