This is an efficacy and safety study of Vytorin (ezetimibe (+) simvastatin) compared to atorvastatin (ezetimibe/simvastatin) at week 6 in primary hypercholesterolemia patients in Korea. The primary hypothesis being tested is that daily administration of Vytorin will result in a greater reduction of low density lipoprotein cholesterol (LDL-C) concentration from baseline after 6 weeks treatment compared to atorvastatin.