I'm pretty sure that copper interconnects are reserved for the 1000mhz+ Athlon parts. Aluminum seems to fail somewhere around 1ghz @u18. "Blue" is the desired core color, where "Green" is not.
This would mean that there are no blue Durons, and even the 1.2ghz blue Athlon seems fairly limited in overclockability. The highest Athlon I've seen is 1.4ghz, (from 1.2ghz, I assume)not nearly as satisfying as the Duron 600 @ 1000.