According to Extreme Tech, "a 2-GHz Atom will be roughly equivalent to the original 1-GHz Dothan (Pentium M) CPU".
Laptoping also reported that "Atom at 1.6GHz is a little bit faster than the old Intel Pentium III-M “Tualatin” at 1.13GHz, but slower than the laptop-use Intel Celeron M “Dothan-512″ at 900MHz, utilized in the Asus Eee PC".
Also, Uberpulse mentioned from a video interview that Silverthorne/Atom is half the performance of the Celeron.
Benchmarks from Notebookreview indicate in terms of CPU performance, Celeron M ULV at 900MHz > Via C7-M ULV at 1.2GHz > Celeron M ULV at 630MHz.
Is Via C7-M ULV at 1.2GHz faster than Intel Atom at 1.6GHz?