Hi, i have talked to my friend and have got a different system configured.
First, i have a PSU question(seeing no forum section for it)
In my local pc store there are these psu for a low price. my friend says that they will break and i should get a more expensive one. they have the watts i need. is my friend right
On to the build: CPU:Intel Core i5-3450 3.1 GHz Processor Motherboard:ASRock H61M-VS Micro ATX LGA1155 Motherboard Memory:Crucial 8GB (2 x 4GB) DDR3-1333 Memory Hard Drive: Kingston SSDNow V200 Series 128GB 2.5" Solid State Disk Graphics Card: XFX Radeon HD 6870 1GB Video Card Case:Xigmatek Asgard II Black/Silver ATX Mid Tower Case Optical DriveSony AD-7280S-0B DVD/CD Writer
I do not claim to be a smart person but here is my opinion anyways.
Actually, I just want to know why you only want a SSD? That SSD will only have 128GB memory and then when you install an OS you will have considerably less memory. I noticed though that you posted it as a $800 build and it is only at $688. A good 1TB HDD can be purchased for the difference pretty easily. I thought I would mention this in the event that you didn't know/realize/or w/e. For all that I know you may have just forgot to put it.
About the PSU, a good PSU is always worth it. If you get a bad PSU then it can cause incredible problems. Something I read on the interwebz was that a golden rule for PSUs is that it should at least cost $10 per watt. (500 watt = $50) I don't know how accurate that is but based on my research it seems to be true for all good or well reviewed PSUs.
Tl;dr: don't skimp on a PSU. Think of it like a man with a power cable pointed at your computer and if you don't pay him well he will fry everything in there just for fun.
Also, I found this FANTASTIC site for building PCs that seems to have everything and lists the prices from many different websites.
Actually, when you format a 120GB SSD, it will have 111GB left. Win 7 Home Premium takes up 20GB. However, you are right that an SSD without a secondary storage isn't a wise choice, especially at an $800 budget. Ditch the SSD and use the $ saved to upgrade the GPU, which is what makes or breaks a gaming build's performance.
Get the Radeon 7850 and OC it - that will give it performance a bit greater than a GTX 570's.