Supported CPU: Socket A AMD Athlon XP/Athlon/Duron Processors
http://www.newegg.com/app/viewProduc...135-143&depa=0
I would have to say your 'reliable source' is not so reliable in this particular case.
He may see that its a 3000+ and assume that a '3000+' is the same no matter what. However in this case it is a 64bit cpu which is different than a 32bit cpu.
Its not just a speed upgrade like going 3000+ to 3200+
http://www.newegg.com/app/ViewProduc...135-147&depa=0
Supported CPU: Socket 754 AMD Athlon64 Processors
This is what you want to see
(I am not endorsing this particular mobo, just wanted to show it explicitly shows support for athlon64)