I would suggest a little more 12v amperage. It's 19A per 12v rail and it features 2 rails. Let me see if I can dig up some specs on the 4850.
EDIT: Based on the specs for a single 4850, I would suggest ~650watt PSU with about 50A between the 12v rails. Yours only has 38A and 600W which would be acceptable, but in the case of a flux, you might corrupt a data process and BSOD. Corsair makes a really nice 650 watt.
Has 650 watts and 52A on a single 12v rail.