Not sure which PSU to get

[bloodandsoil]

How much more would an Enermax Liberty 620W give me compared to an Antec NeoHE 550W?

I'm building a new system with a E6600 C2D and a GeForce 8800GTS.

 

[bloodandsoil]

How do I check the total amps available on the combined +12v rails?

 

[bloodandsoil]

Looks like the Enermax is 36A (432W divided by 12) and the Antec is 42A (504W divided by 12). Sound right?