Complex sentence: In October 2001, the Athlon XP regained a clear lead for AMD, but in January 2002, Intel released Pentium 4s with their new Northwood core at 1.6 GHz, 1.8 GHz, 2 GHz and 2.2 GHz.
Split into simpler sentences: In October 2001, the Athlon XP regained a clear lead for AMD. In January 2002 Intel released Pentium 4s with a new core code named "Northwood" at speeds of 1.6 GHz, 1.8 GHz, 2 GHz and 2.2 GHz.