I'm going with the Silverstone ST45SF-G 450W myself. Modular, gold certified and SFX. Good enough for what I'm putting in the box.All this talk about 600W PSU's makes me curious... Aren't we overestimating our needs for a PSU ?
http://www.extreme.outervision.com/psucalculatorlite.jsp
So basically a 450W PSU would be enough for an already high-end system with a fast GPU. It seems to me the Silverstone SST-ST45SF is a good fit for 70,- or $ 80,- (depending on where you live).
If we downgrade the system a little we even need 50W less:
I myself am considering this last rig with the Silverstone PSU.