I know it seems like that Corsair TX650 that you linked to is the V1 version, as Newegg are listing the part number for that unit, but it is not the V1, because the V1 was not 80 Plus Bronze certified. Also if you look at the pictures, specifically the 4th one, spec label, then you will see the part number is 75-001315. Which means that it is the 'V3'.
The PC Power & Cooling Silencer MK III 600W uses the same internal design as the XFX ProSeries 550W Core Edition, the only advantage it has that I'm aware of is modularity.
To be clear your system won't consume anywhere near 420W, I suspect the calculator you used suggested a PSU wattage of ~420W. So you could use a 450W PSU and still be able to overclock and still have loads of room to spare.
The XFX ProSeries 550W Core Edition is a good choice, but considering that these are the same price before rebate I would personally prefer them:
Rosewill CAPSTONE-450 ($60 @ Amazon / $63 @ Newegg)http://pcpartpicker.com/part/rosewill-power-supply-capstone450
Better than the XFX ProSeries 550W Core Edition because it is independantly regulated and has 80 Plus Gold efficiency.
Rosewill HIVE-550 ($66 @ Amazon)http://pcpartpicker.com/part/rosewill-power-supply-hive550
Better because it is also indy regulated, and modular.