this is my current spec

intel core i3 2100
CM 212+ evo
asrock H77M
2x kingston value ram 6gb (2+4)
1x WD caviar green 500gb
1x samsung spinpoint 80gb
Sapphire HD5770

im planning to buy SeaSonic 520w PSU.

next year, i want to upgrade my pc sort of like this

intel core i5 3rd gen
CM 212+ evo
asrock H77M
2x4gb 1600mhz DDR3
1x WD caviar green 500gb
1x samsung spinpoint 80gb
sapphire HD78XX
add : + SSD
        + DVD writer

my question is will my seasonic 520w support my future upgrade? or should i consider seasonic 620w?  i already use PSU calculator from google searching but every time i calculate, different manufacturer like cooler master, xigmatek, asus give different total watt.

im bit confuse, hope sifu can help. thanks.