Yeah, you're right about the 4400. The 4600 is faster, I guess thats why it costs more. You can check it out on this CPU chart.
http://www23.tomshardware.com/cpu.html? ... model2=234
If I had the choice I would still take the 4400 over the 4600 because it has more cache, the FX series are based on the Toledo core, and it will overclock higher than a Manchester.
However, you are wrong on the PSU. A quality PSU makes a big difference over a generic one. Not all PSUs are created equal. There is a better way of delivering 500W. On a generic PSU the cheap capacitors will age quickly and you will lose wattage. The rails will also have low amps and you will not have a stable system. A quality PSU will give you stable voltages, less ripple, higher efficiency, reliable power output, and longer life.