g-unit1111 posted a reasonable build. ^^^
The graphics card is all important for the gamer.
For balance, budget twice the cpu cost for your graphics card.
In this case, a 2500K or 3570k will be in the $200 ball park.
a GTX670 or 7950 will be less than $400.
budget $100 for a Z77 based motherboard,
a $100 for a hdd or SSD for the os
and $50 for 8gb of ram
and $50 for a case.
$70 for a psu,
Add $100 for a keyboard and mouse, and another $100 for a OS and you are over your budget.
Consider a $120 i3 cpu like the i3-3220 and a $280 graphics card like a 7870 or gtx660ti.
If you live near a microcenter, they will sell you a 3570K for $190, and a 2500k for $160.
But, the 8.5% sales tax is harsh.