See following for game benchmarks; the graphics in the games are maxed out as much as possible so dropping down from Ultra / Very High will give you better performance results. The test rig uses a slightly older Core i7 920 @ 3.8GHz.
well it's obviously ycosting you a little biut more because it's pre-built, but (strange enough) i will say yes, it's worth it. good PC.
cpu + mobo : $350 (no real reason to get the 3770, since the 3570 is just as good)
ram, plenty of it $150
PSU , one that looks awesome $100
a big big HD $100
an awesome SSD $200
DVD - free. well, $17, there.
and then any GPU you want .. (say a 560Ti) less than $200
a cool looking case $50 or more
grand total $1150.
there you have it.
mind you this build squeezes in a SSD, OR you could have a top end card. OR you maybe could have both, just costs a lil'bit more.