...... Ok, now about the your post vietanh
PCIE 3.0 is actually more geared for the future, you will have trouble finding a game these days that will actually max out PCIE 2.0's bandwidth. So 3.0 isn't essential, but it's the best thing to get anyway because Ivy Bridge is currently the most modern CPU, and cost the same as the older ones.
About the RAM part you mentioned... TW seems to be very reliant on RAM speeds and size (which I forgot to mention earlier
), so this is a game when all your RAM specs can make a noticeable difference. 4GB will be fine for an i3 or a low end i5, but if your going with the i5 3570k, then 8GB of RAM will actually be used well.
It's not exactly correct to refer him to Gigabyte. On a budget, ASRock is definitely the best. They offer the exact same hardware features as the bigger brands, like Gigabyte, MSI, and ASUS, but they are a fair bit cheaper. The later 3 brands have better software though. But to be honest, if your on a tight budget, ASRock Z77 boards are they way to go. They also have the least return rates = more reliability. ASUS currently have the highest, which is quite shocking.
For the graphics card.... 7770 is not a good choice, it will only run good on S2 if you pair it with a high end CPU. It's definitely worth investing the few more bucks into a 7850, or better yet, even a few more for the 7870 (owning the best price/performance ratio on the market right now). The lowest end "gaming" graphics cards are the 7850 and 600, any lower and you will notice a huge drop in performance.
Your post on PSU is well stated, but 750W is only going to be necessary for SLI or CFX. My friend has 2 7970's running on a 760W PSU and it never maxes it out, runs amazing.
And yeah, with a HDD you only want to choose between Hitachi, Seagate and Western Digital (in order of reliability; WD most reliable). It's best to get 1TB drives of these, because any higher will have multiple platter = less reliability (although most people wont ever see it fail, so its only a tiny difference, not worth considering, so forget I mentioned it
).