I had my doubts at first about the 4830's, but then I found this review.
Radeon HD 4830 review HIS technology
It seems the 4830 performs very close to the 4850 when it comes to gaming and since its RV770 (LE) it should be able to scale AMAZING in Crossfire. Yeah I know not ALL games support crossfire. But for those games that don't, then a single 4830 should be able to handle them anyways @ reasonable resolutions.
So the PSU in question is an Antec Earth Watt 380 Watts just like Rican has. I remember Rican had 8800 GT's in SLI and his power supply was enough. But I m wondering if it will be able to handle 4830's in Crossfire.