I've assembled PCs in the past, but never my own where I had to choose the parts. I put together the parts from Newegg and needed some help to see if the PSU is enough or any of the parts might give me problems with compatibility.
Here's the build I'm going for.
-ASUS P8Z68-V PRO LGA 1155 Intel Z68 HDMI SATA 6Gb/s USB 3.0 ATX Intel Motherboard with UEFI BIOS
-CORSAIR Vengeance 16GB (4 x 4GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model CML16GX3M4A1600C9B
-ASUS ENGTX580 DCII/2DIS/1536MD5 GeForce GTX 580 (Fermi) 1536MB 384-bit GDDR5 PCI Express 2.0 x16 HDCP Ready SLI Support Video Card
-Seagate Barracuda XT ST32000641AS 2TB 7200 RPM 64MB Cache SATA 6.0Gb/s 3.5" Internal Hard Drive -Bare Drive
-Thermaltake VL200L1W2Z NVIDIA Edition Black and Green Lining ATX Full Tower Gaming Computer Case w/ 2x 120mm Fan (Front & Rear), 1x Front Colorshift LED 120mm Fan, 1x Top Colorshift LED 200mm Fan, 1x Side Colorshift LED 230mm fan & 1x Delta
-SAMSUNG Black 12X BD-ROM 16X DVD-/+R 48X CD-ROM SATA Internal Blu-ray Drive Model SH-B123L/RSBP LightScribe Support (Retail)
-Thermaltake CLP0575 Frio OCK Universal CPU Cooler Ultimate OverClocking King Supports up to 240W TDP Dual 130mm VR Fans
-Microsoft Windows 7 Home Premium
-Thermaltake TPG-750M Toughpower Grand GOLD 750W ATX 12V V2.3 / EPS 12V 2.92 SLI Certified CrossFire Certified 80 PLUS GOLD Certified Modular Active PFC Power Supply
I'm also getting a few extra case fans to increase the cooling.
I'll be overclocking the CPU slightly, and my concern is will the PSU be enough or should I just buy a 850W one ?
Also another question, if I want to add a SSD for the operating system, what's the minimum size that'll be fine for just installing the OS along with a game or 2 ?
memory & cooler:
The CPU cooler and the memory will most likely have clearance issues.
Check for memory with lower profile heatsinks from Corsair, Gskill, Kingston or Mushkin.
The 750W PSU is enough as long as you don't intend to SLI the 580.
For that price:$179.99 you can do so much better with the PSU. You don't really get what you pay for.
jonnyguru only gives it a 8.5 (here)
So if you want the best at 750W: Seasonic X750 or X760 ~ $159.99 you can't go wrong here. It's pretty much the best you can get. 9.5 rating ( link )
Corsair HX850 is also one of my favorites in this price range and performance. 9.6 rating (link)
If you intend to SLI the 580, look for PSU's in the 1000W range.
Corsair AX 1200 (1200W) would be the best, but there are several good ones at 1000W as well ocz zx series for example.
Minimum size depends on the game, but i would say 64GB is the absolute minimum: Crucial M4 would be nice.
But basically for much more than OS and apps, 120GB is the way to go.