Even when only clocked with 1GHz, the AMD Athlon 2000+ clearly beats the Atom single-core and comes close to the Atom dual-core. If AMD can pull out a single-core CPU which clocks with 1.30GHz it can clearly beat even the Atom dual-core. The AMD Athlon 64 X2 3400e is in an entirely different league, it's like fusion-drive against hyper-drive.
Atom 330 dual-core 1.60GHz for reference:
AMD Athlon 64 2000+:
AMD Athlon 64 X2 3400e single-threaded:
AMD Athlon 64 X2 3400e:
Sandra shows similar results, but we didn't bother to test the AMD Athlon 2000+, because it's slower compared to the standard Atom single-cores clocked at 1.60GHz.