I've decided I'm crazy enough to want to build my own computer despite my complete lack of experience of doing anything beyond swapping out ram and a graphics card. Mostly because my old desky, in addition to being inconvenient for me to access for a while, is getting really old in some key areas, and because I need to conserve liquid assets at the moment and I won't buy my usual vendor (Dell) anymore when I can just build it myself for a lot cheaper. Assuming I can actually figure out what parts are right and how to do it. I might be receiving help from a friend who's done it once before, but I might not.
Since most of the games I want to play are already out for a while (my desky couldn't handle them very well because it's a Pentium D) or are about to come out, so I'm perfectly fine with this not being a super-duper-long term build. If it can play Skyrim, ME3, TOR/GW2, and/or The Witcher 2 on high detail with FPS consistently at or above 50-60fps, I'm good. Especially if I can upgrade later.
What I'm looking for is a barebones (ie, under 700, preferably even lower. As low as possible) gaming pc that can play that stuff fine. Monitors, perpherals, and the OS do not not need to be taken into account. My general idea for specs:
Intel Core i3 3.0-3.3 mHz, or if that's just too expensive
Phenom II X4 of similar clock speed
A motherboard that can handle those two
A Radeon 6770 or 6850, from research the best vendors seem to be Sapphire (good experience previously), MSI, HIS, and Asus
4 GB Ram (Crucial? Kingston? 1333? 1600? Does it really matter?)
A 500 GB HD (expensive I know thanks to the Thailand floods, but they might stay high for a year and I don't want to wait that long)
A 600W Power Supply (is that too much W for one radeon?)
And actually want a cheap Creative SC instead of the onboard stuff. Not sure what I need as far as motherboard connections go though
A case that will comfortably fit all of this
By biggest issue is getting the motherboard right, making sure a big graphics card doesn't make the SATA connections inaccessible (which is a problem with Gigabyte boards apparently, which is driving me towards ASUS) and there are enough connections for everything I want, etc.
And I do not care where or how I get the parts, so long as I am not running a risk of being scammed or getting something DOA with horrible customer service.
I know a lot of you have experience with building machines, so advice would be appreciated. Am I going about this the wrong way?