It depends on your budget. That's almost always the case. The P4 indeed costs more, but the platform you can put it on (with an Intel chipset), you get practically guaranteed stability/compatibility. No problems with infinite loops, XP, nvidia drivers, sblive drivers, ati drivers, etc. But again, there is the cost. AthlonXP solutions perform just as well on average and costs less. From a performance standpoint, there is no real difference. So basically, it's price vs stability/compatibility.