Is my build good enough - if not suggestions are welcome

Seems solid to me. Be sure to get 2x4Gb RAM to take advantage of dual-channel!

It will handle those games at 6o fps at highest settings . Also i would suggest dual-channel Ram and lower the speed at 1600Mhz , it doesnt make a difference unless you are editing big HD videos

To see the proper slots check the manual of your motherboard

Hey WookieMonster-- I like how you think, DIY is the way to go. If you already pulled the trigger on these parts than By all means have fun. If however you haven't I wanted to caution you on a few things. THIS IS IMPORTANT THOUGH- if you want to get these parts for sure-- STOP READING THIS...but...
If you genuinely want some feed back I'll give some thought (my opinion for sure)
Are you getting the 8818Bcase? the ones with the side fans? if so, they may be competing against your Zalman Heat sink (Newegg folks claim there loud too) Consider a small tower over this thing-- it will vent out the back too--if you are getting the case with the cool tornado thing with a big window it looks really sweet and I prefer looking at the parts but you'll wanna get some lights-- to show & shine off your cool gear. I have a i5-3570K on an Asus P8Z77-V LK and ya you can overclock, but not to 4400 easily-- specs are 3.4 to 3.8, no matter though it's fast. Gigabyte's UEFI looks way sweet and user friendly.. I would suggest a Cache drive (Sandisk Ready cache) about $40, that will make a world of difference with surfing, boot time and program launch..of course you could get a 120gb SSD later-- you'll love that for sure...Will that low profile Zalman clear the Memory slots? you may want to measure the distance between the CPU center and the first DIMM slot to be sure,I have 8GB of Corsair Vegeance ram too and it works just fine. (True, get the 2x4gb kit others suggested). A 700 Watt PSU is capable of driving these components, but consider the 7870 draws 150 watts and needs an 8 pin (6 +2)... and the card's 10"+ long.. I know when I installed my 7850 My case and the extra PCIe slot looked lonely, so I go another and ran crossfire...PLEASE consider that if you want to add another 7870 later on (and you will)that PSU may not handle-- additionally you'll need another 6+2, which the PSU may not have...I can run the S*** out these games on Max with 2 7850 Sapphire 2GB models (and AMD has GREAT incentives on Bundle games now too-- as WELL AS 13.8 driver). Finally get win 7-- everyone bitchs about 8 as you know...Well sorry for the long answer Dude-- Hope it helps

For a cheaper price you can get a lot better AMD build. Check out this rig

PCPartPicker part list / Price breakdown by merchant / Benchmarks

CPU: AMD FX-8350 4.0GHz 8-Core Processor (£143.99 @ Aria PC)
CPU Cooler: Cooler Master Hyper 212 EVO 82.9 CFM Sleeve Bearing CPU Cooler (£22.85 @ CCL Computers)
Motherboard: ASRock 970 EXTREME4 ATX AM3+ Motherboard (£74.36 @ Scan.co.uk)
Memory: Patriot Viper Xtreme 8GB (2 x 4GB) DDR3-1866 Memory (£45.35 @ Amazon UK)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive (£46.80 @ Aria PC)
Video Card: Sapphire Radeon HD 7950 3GB Video Card (£199.99 @ Aria PC)
Wireless Network Adapter: Asus PCE-N15 802.11b/g/n PCI-Express x1 Wi-Fi Adapter (£14.99 @ CCL Computers)
Case: Zalman Z5 Plus ATX Mid Tower Case (£38.99 @ Novatech)
Power Supply: Corsair Builder 750W 80 PLUS Bronze Certified ATX12V / EPS12V Power Supply (£66.90 @ Scan.co.uk)
Optical Drive: Samsung SH-224DB/BEBE DVD/CD Writer (£12.86 @ Amazon UK)
Operating System: Microsoft Windows 7 Home Premium SP1 (OEM) (64-bit) (£68.39 @ Aria PC)
Total: £735.47
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2013-08-20 08:12 BST+0100)