Though the 550W is peak rating (it is really a 500W unit), HardwareSecrets gave that one a golden award; previous Rocketfish PSU-shaped objects were generally IED's that snapped crackled and popped when tested.
I agree with ScrewySqrl except for the MSI mobo. I'd choose one from ASRock that also includes USB 3.0 and SATA 6Gb/s.
from the Hardware Secrets review, the 550 (really 500W) PSU is 'good enough' for what it is. It's limited by a single 6-pin output, so a 7770, 6850 or 7850 are your only real options for a video card, along with low-end options that use just the PCIe power. No NVidia cards that use a single 6-pin are worth the price.
I'd use it with any of those 3 cards, but nothing higher power than that.
If you use that PSU, you save the $35 from the Antec 450W, and if you add another $100, you can afford to change from the 7770 to a HD7850, which along with the i5-2400 wll keep you gaming into 2014, at least