Upgrading to a GTX 460

[Decennium]

I'm planning on upgrading my 4850 to a GTX 460. I currently have a BFG GS-550W PSU, will that be enough? Also would it be able to fit in my Antec 300 case?

 

[Decennium]

K thanks for the reply, By the way which GTX 460 should I buy? I was thinking the 1gb MSI Cyclone.

 

[Decennium]

Best answer selected by Decennium.