Rawbunnie :
Apparently its not "very, very difficult" seeing as the build i posted will max out almost all games out there....
Pretty nice build overall. Very impressive in fact (I'm in Canada BTW which is sometimes good and sometimes bad for PC building).
Some minor points:
1) That PSU blew up on me within one day. sure, these things happen, but then I did more research it seems that the Corsair Builder series has had a disproportionate share of bad PSU's. Possibly why the Corsair CX430 is only $25. I got a different Antec for more money.
2) Nothing wrong with the GTX660 (I have a 680), but it's worth pointing out that the HD7000 series have some pretty good games included. As I said above for the HD7850, I didn't consider the extra money over a cheaper card part of the overall $600 cost though if those games were of interest (roughly $110 value those 2.5 games).
3) I always recommend a non-stock CPU cooler, even if only $20 as stock coolers are usually fairly noisy and a pain to replace later.
4) For the build price your CPU is also correct. If a little more money could be added ("around" $600) I'd probably recommend the FX-6300.
5) START8 (it's only $5 but I should add it again if I'm going to compare)
So... nice build overall.
Please realize I'm not ripping your build apart. For the price that's about as good as you can do. In fact, it's pretty amazing that a gaming PC could be built that cheaply.
My only big issue is the Power Supply. Having build 100+ systems over the years, I tend to be very cautious (actually the Corsair CX430 is the ONLY power supply that died on me in about 20 years of building).