I really like using a ssd for the os and a few games. The price is getting down to <$1 per gb.
If you can budget for a 120gb ssd, why not omit the hard drive in the first place?
120gb will hold the os and 6-8 games.
Here is an Intel 330 180gb ssd, it should be all you need for a while. Add a hard drive later if you need to: http://www.newegg.com/Product/Product.aspx?Item=N82E168...
The 120gb version is $150.
It is not wrong to overprovision the psu a bit.
Under load, the fan will not spin up so much and get noisy.
The Corsair buider series are good value units, 500w or 600w would be fine.
The GTX560ti needs a bit more than the GTX560.