Depends on what you are expecting out of your system. If the new P4 chip will work with your present motherboard then it will be much cheaper going this route. 1.5 to 2.0 is not that big of a jump. If you can find a 2.3,2.5 or 2.6 for not much more $ then I would probably stick in the fastest cpu that I could afford. (All numbers were rounded up)
Virgin Techie, that is a pretty old article that you referenced. Notice that Crazed_Climber is considering a 2600+ AMD which is supposed to run on a level with the P4 2.6 (Neither of the chips tested are used with what today is considered the idea motherboard and chipset)
3 different OS, so yep I\'m confused.