Core 2 Duo is a dual-core. It would help a lot if we knew what exact dual-core you're referring to by "Dual Core 2.0GHz". Generally, though, Core2Duo > Pentium Dual-Core > Celeron Dual-Core > Athlon (64) X2 > Pentium D as far as clock-for-clock performance is concerned.Is it better to have Dual Core 2.0GHz or to have Core 2 Duo 1.6 GHz?