First off, the processor that you selected, the AMD FX-4170 for $104.99 @http://www.newegg.com/Product/Product.aspx?Item=N82E16819106009&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-_-na-_-na-_-na&AID=10446076&PID=3938566&SID=, is clocked at 4.2Ghz. It's a low budget processor and not suited well for graphics intensive games, also when talking about AMD processors you cannot directly relate that to Intel processors, it's equivalent of comparing an apple to an orange.
For better performance at a similar pricing point I suggest the Intel Core i3-3225 for $129.99 @http://us.ncix.com/products/?sku=75430&vpn=BX80637I33225&manufacture=Intel&promoid=1016.
Secondly, The motherboard that you have selected, the GIGABYTE GA-78LMT-USB3 for $62.99 @http://us.ncix.com/products/?sku=75286&vpn=GA%2D78LMT%2DUSB3&manufacture=Gigabyte&promoid=1286, is a Micro-ATX and is a very low end motherboard. If you are going with my afformentioned processor then you will need a different motherboard to be compatible.
Around the same price, with more features and an ATX form factor, there is the ASRock B75 PRO3 for $82.55 @http://www.newegg.com/Product/Product.aspx?Item=N82E16813157314&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-_-na-_-na-_-na&AID=10446076&PID=3938566&SID=.
Thirdly, the graphics card that you have selected, the AMD HD 6670 2GB for $59.99 @http://www.microcenter.com/product/396145/H667FR2G_AMD_Radeon_HD_6670_2048MB_DDR3_PCIe_X16_21_Video_Card, is a low-mid range graphics card and I figure would do fine as a graphics card, in fact in it's price range it has the most memory from what I can see, so keep that.
EDIT: For the graphics card, if you want to game on high settings you will need to drop more money on it, I am not going to suggest anything but I am just bringing this to your attention.
Fourth, the memory that you have selected is quite vague "8GB" does not tell me what so I will find link to you some cheap, compatible memory that I think you should purchase, the 1600Mhz 8GB Kingston HyperX T1 for $25.99 @http://www.newegg.com/Product/Product.aspx?Item=N82E16820104242&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-_-na-_-na-_-na&AID=10446076&PID=3938566&SID=.
Fifth, the hard drive you selected is also nebulous, so for you should purchase the Seagate Barracuda 1TB 7200RPM 64MB SATA 6Gbps for $69.99 @http://us.ncix.com/products/?sku=65701&vpn=ST1000DM003&manufacture=Seagate&promoid=1016.
Sixth, you didn't say what optical drive you want ( You simply said "Yes" ) so I am going to push the LITE-ON DVD Burner for $17.99 @http://www.newegg.com/Product/Product.aspx?Item=N82E16827106289&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-_-na-_-na-_-na&AID=10446076&PID=3938566&SID=
Seventh, you don't need a PCI network card, it's integrated into your motherboard.
Lastly, your power supply is actually kind of hard to find so I don't know the pricing point of it. Just get the OCZ StealthXStream 2 600W ( 80 PLUS certified )for $39.99 @http://us.ncix.com/products/?sku=53966&vpn=OCZ600SXS2&manufacture=OCZ%20Technology&promoid=1146.
My Parts Total: $426.49USD after rebate but before taxes
I hope I could help you on your computer building endeavour, and as always, good luck.