diff Btwn P4(1.4-1.7) and anthlon 1.3

can you please advice me on these products, because I’m trying to buy a new p.c. and I would like to know, the difference in performance between pentium processor 1.4, 1.5, 1.7, and Anthlon amd 1.2 processor. I would also like to know your recommendations on Dell products.