A05 is the final silicon for the Geforce 3, the beta boards that some site got a long time ago were A03, they had to do a few changes to increase stability(get the bugs out) and, as i here, the chip now overclocks better to.
I'm still waiting to get one over here in the U.K. as they have not yet been formally released
P.S. I'd like to know what the image quality is like compared the your G450, as i have the G400